Context: dotnet/android#8543
Context: dotnet/android#8625
Context: #1168
Context: def5bc0
Context: 005c914

dotnet/android#8543 tested PR #1168, was Totally Green™ --
finding no issues -- and so we merged PR #1168 into 005c914.

Enter dotnet/android#8625, which bumps xamarin-android to
use def5bc0, which includes 005c914.  dotnet/android#8625
contains *failing unit tests* (?!), including
`Java.InteropTests.InvokeVirtualFromConstructorTests()`:

	Java.Lang.LinkageError : net.dot.jni.test.CallVirtualFromConstructorDerived
	----> System.NotSupportedException : Could not find System.Type corresponding to Java type JniTypeSignature(TypeName=net/dot/jni/test/CallVirtualFromConstructorDerived ArrayRank=0 Keyword=False) .
	   at Java.Interop.JniEnvironment.StaticMethods.GetStaticMethodID(JniObjectReference , String , String )
	   at Java.Interop.JniType.GetStaticMethod(String , String )
	   at Java.Interop.JniPeerMembers.JniStaticMethods.GetMethodInfo(String , String )
	   at Java.Interop.JniPeerMembers.JniStaticMethods.GetMethodInfo(String )
	   at Java.Interop.JniPeerMembers.JniStaticMethods.InvokeObjectMethod(String , JniArgumentValue* )
	   at Java.InteropTests.CallVirtualFromConstructorDerived.NewInstance(Int32 value)
	   at Java.InteropTests.InvokeVirtualFromConstructorTests.ActivationConstructor()
	   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
	   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object , BindingFlags )
	  --- End of managed Java.Lang.LinkageError stack trace ---
	java.lang.NoClassDefFoundError: net.dot.jni.test.CallVirtualFromConstructorDerived
		at crc643df67da7b13bb6b1.TestInstrumentation_1.n_onStart(Native Method)
		at crc643df67da7b13bb6b1.TestInstrumentation_1.onStart(TestInstrumentation_1.java:35)
		at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:2189)
	Caused by: android.runtime.JavaProxyThrowable: [System.NotSupportedException]: Could not find System.Type corresponding to Java type JniTypeSignature(TypeName=net/dot/jni/test/CallVirtualFromConstructorDerived ArrayRank=0 Keyword=False) .
		at Java.Interop.ManagedPeer.GetTypeFromSignature(Unknown Source:0)
		at Java.Interop.ManagedPeer.RegisterNativeMembers(Unknown Source:0)
		at net.dot.jni.ManagedPeer.registerNativeMembers(Native Method)
		at net.dot.jni.test.CallVirtualFromConstructorDerived.<clinit>(CallVirtualFromConstructorDerived.java:12)
		... 3 more

	--NotSupportedException
	   at Java.Interop.ManagedPeer.GetTypeFromSignature(JniTypeManager , JniTypeSignature , String )
	   at Java.Interop.ManagedPeer.RegisterNativeMembers(IntPtr jnienv, IntPtr klass, IntPtr n_nativeClass, IntPtr n_methods)

:shocked-pikachu-face: (But dotnet/android#8543 was green!)

The problem is twofold:

 1. 005c914 now requires the presence of typemap entries from e.g.
    `Java.InteropTests.CallVirtualFromConstructorDerived` to
    `net.dot.jni.test.CallVirtualFromConstructorDerived`.

 2. `Java.Interop.Tools.JavaCallableWrappers` et al doesn't create
    typemap entries for `Java.Interop.JavaObject` subclasses which
    have `[JniTypeSignature]`.

Consequently, our units tests fail (and apparently weren't *run* on
dotnet/android#8543?!  Still not what happened.)

Fix typemap generation by adding a new `TypeDefinition.HasJavaPeer()`
extension method to replace all the `.IsSubclassOf("Java.Lang.Object")`
and similar checks, extending it to also check for
`Java.Interop.JavaObject` and `Java.Interop.JavaException` base types.
(Continuing to use base type checks is done instead of just relying
on implementation of `Java.Interop.IJavaPeerable` as a performance
optimization, as there could be *lots* of interface types to check.)

Additionally, @jonathanpeppers -- while trying to investigate all
this -- ran across a build failure:

	obj\Debug\net9.0-android\android\src\java\lang\Object.java(7,15): javac.exe error JAVAC0000:  error: cyclic inheritance involving Object

This suggests that `Java.Interop.Tools.JavaCallableWrappers` was
encountering `Java.Interop.JavaObject` -- or some other type which
has `[JniTypeSignature("java/lang/Object")]` -- which is why
`java/lang/Object.java` was being generated.

Audit all `[JniTypeSignature]` attributes, and add
`GenerateJavaPeer=false` to all types which should *not* hava a
Java Callable Wrapper generated for them.  This includes nearly
everything within `Java.Interop-Tests.dll`.  (We want the typemaps!
We *don't* want generated Java source, as we have hand-written Java
peer types for those tests.)

---

Aside: this project includes [T4 Text Templates][0].  To regenerate
the output files *without involving Visual Studio*, you can install
the [`dotnet-t4`][1] tool:

	$ dotnet tool install --global dotnet-t4

then run it separately for each `.tt` file:

	$HOME/.dotnet/tools/t4 -o src/Java.Interop/Java.Interop/JavaPrimitiveArrays.cs \
	  src/Java.Interop/Java.Interop/JavaPrimitiveArrays.tt

[0]: https://learn.microsoft.com/visualstudio/modeling/code-generation-and-t4-text-templates?view=vs-2022
[1]: https://www.nuget.org/packages/dotnet-t4/

A funny thing happened when b9aa5f7 ran on xamarin-android:
unit tests started crashing!

	E monodroid-assembly: typemap: unable to load assembly 'Java.Interop-Tests' when looking up managed type corresponding to Java type 'java/lang/Object'

What appears to be happening is an Unfortunate Interaction™:

 1. `Java.Interop-Tests.dll` contained *multiple bindings* for
    `java/lang/Object`. e.g.

        [JniTypeSignature ("java/lang/Object", GenerateJavaPeer=false)]
        partial class JavaDisposedObject : JavaObject {
        }

 2. The typemap generator has no functionality to "prioritize" one
    binding vs. another; it's random.  As such, there is nothing to
    cause `Java.Lang.Object` to be used as the preferred binding for
    `java/lang/Object`.

This meant that when we hit the typemap codepath in .NET Android,
we looked for the C# type that corresponded to `java/lang/Object`,
found *some random type* from `Java.Interop-Tests`, and…

…and then we hit another oddity: that codepath only supported looking
for C# types in assemblies which had already been loaded.  This was
occurring during startup, so `Java.Interop-Tests` had not yet been
loaded yet, so it errored out, returned `nullptr`, and later Android
just aborts things:

	F droid.NET_Test: runtime.cc:638] JNI DETECTED ERROR IN APPLICATION: use of deleted local reference 0x79

Just…eep!

This didn't happen before because `Java.Interop.JavaObject` subclasses
*didn't* participate in typemap generation.  b9aa5f7 *added* that
support, introducing this unforeseen interaction.

Fix this by *removing* all "alternate bindings" for `java/lang/Object`:

	- [JniTypeSignature ("java/lang/Object", GenerateJavaPeer=false)]
	+ [JniTypeSignature (JniTypeName)]
          partial class JavaDisposedObject : JavaObject {
              internal const string JniTypeName = "net/dot/jni/test/JavaDisposedObject";
          }

This implicitly requires that we now have a Java Callable Wrapper
for this type, so update `Java.Interop-Tests.csproj` to run `jcw-gen`
as part of the build process.  This ensures that we create the
JCW for e.g. `JavaDisposedObject`.

Finally, update `JavaVMFixture` to add the required typemap entries.

These changes should allow .NET Android unit tests to run w/o crashing.

…upport

This type mapping isn't *actually* required, but it *is* used in
`JavaVMFixture`, and it confuses people (me!) if things are
inconsistent.

CI is failing with:

	Java.Interop-Tests -> /Users/runner/work/1/s/bin/TestRelease-net7.0/Java.Interop-Tests.dll
	Could not execute because the specified command or file was not found.
	Possible reasons for this include:
	  * You misspelled a built-in dotnet command.
	  * You intended to execute a .NET program, but dotnet-/Users/runner/work/1/s/bin/Release-net7.0//jcw-gen.dll does not exist.
	  * You intended to run a global tool, but a dotnet-prefixed executable with this name could not be found on the PATH.
	##[error]tests/Java.Interop-Tests/Java.Interop-Tests.targets(26,5): Error MSB3073: The command "dotnet "/Users/runner/work/1/s/bin/Release-net7.0//jcw-gen.dll" -v "/Users/runner/work/1/s/bin/TestRelease-net7.0/Java.Interop-Tests.dll" --codegen-target JavaInterop1 -o "obj/Release-net7.0//java" -L "/Users/runner/work/1/s/bin/Release-net7.0/ref/." -L "/Users/runner/work/1/s/bin/TestRelease-net7.0/ref/." -L "/Users/runner/hostedtoolcache/dotnet/packs/Microsoft.NETCore.App.Ref/7.0.15/ref/net7.0/." -L "/Users/runner/.nuget/packages/microsoft.testplatform.testhost/17.5.0-preview-20221003-04/lib/netcoreapp3.1/." -L "/Users/runner/.nuget/packages/microsoft.codecoverage/17.5.0-preview-20221003-04/lib/netcoreapp3.1/." -L "/Users/runner/.nuget/packages/mono.linq.expressions/2.0.0/lib/netstandard2.0/." -L "/Users/runner/.nuget/packages/mono.options/6.12.0.148/lib/netstandard2.0/." -L "/Users/runner/.nuget/packages/newtonsoft.json/13.0.1/lib/netstandard2.0/." -L "/Users/runner/.nuget/packages/nuget.frameworks/5.11.0/lib/netstandard2.0/." -L "/Users/runner/.nuget/packages/nunit/3.13.2/lib/netstandard2.0/." -L "/Users/runner/work/1/s/external/xamarin-android-tools/bin/Release/net6.0/ref/."" exited with code 1.
	/Users/runner/work/1/s/tests/Java.Interop-Tests/Java.Interop-Tests.targets(26,5): error MSB3073: The command "dotnet "/Users/runner/work/1/s/bin/Release-net7.0//jcw-gen.dll" -v "/Users/runner/work/1/s/bin/TestRelease-net7.0/Java.Interop-Tests.dll" --codegen-target JavaInterop1 -o "obj/Release-net7.0//java" -L "/Users/runner/work/1/s/bin/Release-net7.0/ref/." -L "/Users/runner/work/1/s/bin/TestRelease-net7.0/ref/." -L "/Users/runner/hostedtoolcache/dotnet/packs/Microsoft.NETCore.App.Ref/7.0.15/ref/net7.0/." -L "/Users/runner/.nuget/packages/microsoft.testplatform.testhost/17.5.0-preview-20221003-04/lib/netcoreapp3.1/." -L "/Users/runner/.nuget/packages/microsoft.codecoverage/17.5.0-preview-20221003-04/lib/netcoreapp3.1/." -L "/Users/runner/.nuget/packages/mono.linq.expressions/2.0.0/lib/netstandard2.0/." -L "/Users/runner/.nuget/packages/mono.options/6.12.0.148/lib/netstandard2.0/." -L "/Users/runner/.nuget/packages/newtonsoft.json/13.0.1/lib/netstandard2.0/." -L "/Users/runner/.nuget/packages/nuget.frameworks/5.11.0/lib/netstandard2.0/." -L "/Users/runner/.nuget/packages/nunit/3.13.2/lib/netstandard2.0/." -L "/Users/runner/work/1/s/external/xamarin-android-tools/bin/Release/net6.0/ref/."" exited with code 1. [/Users/runner/work/1/s/tests/Java.Interop-Tests/Java.Interop-Tests.csproj]

Add a `@(ProjectReference)` from `Java.Interop-Tests.csproj`
to `jcw-gen.csproj` to ensure that `jcw-gen.csproj` is built first.

Fix typo.  (What's a "cit"?)