[Java.Interop] Support System.Byte, somewhat

[jonpryor]

Context: dotnet/android#9747
Context: dotnet/android#9812

In the ongoing epic to get MAUI running atop NativeAOT, we hit our longstanding NativeAOT nemesis: P/Invoke:

E AndroidRuntime: net.dot.jni.internal.JavaProxyThrowable: System.InvalidProgramException: InvalidProgram_Specific, IntPtr Android.Runtime.JNIEnv.monodroid_typemap_managed_to_java(System.Type, Byte*)
E AndroidRuntime:    at Internal.Runtime.TypeLoaderExceptionHelper.CreateInvalidProgramException(ExceptionStringID, String) + 0x4c
E AndroidRuntime:    at Android.Runtime.JNIEnv.monodroid_typemap_managed_to_java(Type, Byte*) + 0x18
E AndroidRuntime:    at Android.Runtime.JNIEnv.TypemapManagedToJava(Type) + 0x104
E AndroidRuntime:    at Android.Runtime.JNIEnv.GetJniName(Type) + 0x1c
E AndroidRuntime:    at Android.Runtime.JNIEnv.FindClass(Type) + 0x38
E AndroidRuntime:    at Android.Runtime.JNIEnv.NewArray(IJavaObject[]) + 0x28
E AndroidRuntime:    at Android.Runtime.JNIEnv.NewArray[T](T[]) + 0x94
E AndroidRuntime:    at Android.Graphics.Drawables.LayerDrawable..ctor(Drawable[] layers) + 0xd4
E AndroidRuntime:    at Microsoft.Maui.Platform.MauiRippleDrawableExtensions.UpdateMauiRippleDrawableBackground(View, Paint, IButtonStroke, Func`1, Func`1, Action) + 0x2ac

(JNIEnv.monodroid_typemap_managed_to_java() is P/Invoke.)

The reasonable fix/workaround: update JNIEnv.FindClass(Type) to instead use JniRuntime.JniTypeManager.GetTypeSignature(Type). (Also known as "embrace more JniRuntime abstractions!".)

Unfortunately, this straightforward idea hits a minor schism between the .NET for Android and builtin java-interop world orders:

How should Java byte be bound?

For starters, what is a Java byte?

The values of the integral types are integers in the following ranges:

• For byte, from -128 to 127, inclusive

The Java byte is signed! Because of that, and because java-interop originated as a Second System Syndrome rebuild of Xamarin.Android, of course java-interop bound Java byte as System.SByte.

.NET for Android, though, bound Java byte as System.Byte.

This "minor" change meant that lots of unit tests started failing, e.g. NetworkInterfacesTest.DotNetInterfacesShouldEqualJavaInterfaces():

System.ArgumentException : Could not determine Java type corresponding to System.Byte[], System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e. Arg_ParamName_Name, type
   at Android.Runtime.JNIEnv.FindClass(Type )
   at Android.Runtime.JNIEnv.AssertCompatibleArrayTypes(IntPtr , Type )
   at Android.Runtime.JNIEnv._GetArray(IntPtr , Type )
   at Android.Runtime.JNIEnv.GetArray(IntPtr , JniHandleOwnership , Type )
   at Java.Net.NetworkInterface.GetHardwareAddress()
   at System.NetTests.NetworkInterfacesTest.GetInfos(IEnumeration interfaces)
   at System.NetTests.NetworkInterfacesTest.DotNetInterfacesShouldEqualJavaInterfaces()
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object , BindingFlags )

Rephrased, runtime.TypeManager.GetTypeSignature(typeof(byte[])) returned a "default" JniTypeSignature instance.

It's time to reduce the size of this schism.

Update JniBuiltinMarshalers.GetBuiltInTypeSignature() so that TypeCode.Byte is treated as a synonym for TypeCode.SByte. This is in fact all that's needed in order to add support for byte[]!

It's not all that's necessary to fix all unit tests.

Update JniRuntime.JniTypeManager.GetTypeSignature() and .GetTypeSignatures() so that if the type is an open generic type a System.NotSupportedException is thrown instead of a System.ArgumentException. This fixes
Java.InteropTests.JnienvTest.NewOpenGenericTypeThrows().

Also, JniBuiltinMarshalers.cs got some hand-made changes, rendering it out of sync with JniBuiltinMarshalers.tt. Regenerate it.

[jonpryor]

/azp run

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[jonpryor]

[Java.Interop] .GetTypeSignature() supports unsigned types (#1312)

Context: https://github.com/dotnet/android/pull/9747
Context: https://github.com/dotnet/android/pull/9812
Context: 71afce55812fc2c5efd6002580b539d8394f7bca
Context: https://github.com/dotnet/android/commit/aa5e597ebacce385ac96bc91bd10453e65608634
Context: https://github.com/dotnet/android/commit/f800c1a6ee8d584f28d6b7a03485b7091e2d3115

In the ongoing epic to get MAUI running atop NativeAOT, we hit our
longstanding NativeAOT nemesis: a P/Invoke:

	E AndroidRuntime: net.dot.jni.internal.JavaProxyThrowable: System.InvalidProgramException: InvalidProgram_Specific, IntPtr Android.Runtime.JNIEnv.monodroid_typemap_managed_to_java(System.Type, Byte*)
	E AndroidRuntime:    at Internal.Runtime.TypeLoaderExceptionHelper.CreateInvalidProgramException(ExceptionStringID, String) + 0x4c
	E AndroidRuntime:    at Android.Runtime.JNIEnv.monodroid_typemap_managed_to_java(Type, Byte*) + 0x18
	E AndroidRuntime:    at Android.Runtime.JNIEnv.TypemapManagedToJava(Type) + 0x104
	E AndroidRuntime:    at Android.Runtime.JNIEnv.GetJniName(Type) + 0x1c
	E AndroidRuntime:    at Android.Runtime.JNIEnv.FindClass(Type) + 0x38
	E AndroidRuntime:    at Android.Runtime.JNIEnv.NewArray(IJavaObject[]) + 0x28
	E AndroidRuntime:    at Android.Runtime.JNIEnv.NewArray[T](T[]) + 0x94
	E AndroidRuntime:    at Android.Graphics.Drawables.LayerDrawable..ctor(Drawable[] layers) + 0xd4
	E AndroidRuntime:    at Microsoft.Maui.Platform.MauiRippleDrawableExtensions.UpdateMauiRippleDrawableBackground(View, Paint, IButtonStroke, Func`1, Func`1, Action) + 0x2ac

(`JNIEnv.monodroid_typemap_managed_to_java()` is P/Invoke.  Why are
P/Invokes bad?  See dotnet/android@f800c1a6.)

The reasonable fix/workaround: update `JNIEnv.FindClass(Type)` to
instead use `JniRuntime.JniTypeManager.GetTypeSignature(Type)`.
(Also known as "embrace more JniRuntime abstractions!".)

Unfortunately, this straightforward idea hits a minor schism between
the .NET for Android and builtin java-interop world orders:

How should Java `byte` be bound?

For starters, what *is* a [Java `byte`][0]?

> The values of the integral types are integers in the following ranges:
>
>   * For `byte`, from -128 to 127, inclusive

The Java `byte` is *signed*!  Because of that, and because
java-interop originated as a Second System Syndrome rebuild of
Xamarin.Android, *of course* java-interop bound Java `byte` as
`System.SByte`.

.NET for Android, though, bound Java `byte` as `System.Byte`.

This "minor" change meant that lots of unit tests started failing, e.g.
[`NetworkInterfacesTest.DotNetInterfacesShouldEqualJavaInterfaces()`][2]:

	System.ArgumentException : Could not determine Java type corresponding to System.Byte[], System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e. Arg_ParamName_Name, type
	   at Android.Runtime.JNIEnv.FindClass(Type )
	   at Android.Runtime.JNIEnv.AssertCompatibleArrayTypes(IntPtr , Type )
	   at Android.Runtime.JNIEnv._GetArray(IntPtr , Type )
	   at Android.Runtime.JNIEnv.GetArray(IntPtr , JniHandleOwnership , Type )
	   at Java.Net.NetworkInterface.GetHardwareAddress()
	   at System.NetTests.NetworkInterfacesTest.GetInfos(IEnumeration interfaces)
	   at System.NetTests.NetworkInterfacesTest.DotNetInterfacesShouldEqualJavaInterfaces()
	   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
	   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object , BindingFlags )

Rephrased, `runtime.TypeManager.GetTypeSignature(typeof(byte[]))`
returned a "default" `JniTypeSignature` instance.

It's time to reduce the size of this schism.

Update `JniBuiltinMarshalers.GetBuiltInTypeSignature()` so that
`TypeCode.Byte` is treated as a synonym for `TypeCode.SByte`.
This is in fact all that's needed in order to add support for `byte[]`!

Repeat this exercise for all other unsigned types: `ushort`, `uint`,
and `ulong`, as Kotlin unsigned types require it; see also 71afce55
and dotnet/android@aa5e597eba.  This fixes the exception:

	System.InvalidCastException : Unable to cast from '[I' to '[Ljava/lang/Object;'.
	   at Android.Runtime.JNIEnv.AssertCompatibleArrayTypes(IntPtr , Type )
	   at Android.Runtime.JNIEnv._GetArray(IntPtr , Type )
	   at Android.Runtime.JNIEnv.GetArray(IntPtr , JniHandleOwnership , Type )
	   at Foo.UnsignedInstanceMethods.UintArrayInstanceMethod(UInt32[] value)
	   at Xamarin.Android.JcwGenTests.KotlinUnsignedTypesTests.TestUnsignedArrayTypeMembers()
	   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
	   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object , BindingFlags )

This is *not* all that's necessary to fix all dotnet/android tests.

Update `JniRuntime.JniTypeManager.GetTypeSignature()` and
`.GetTypeSignatures()` so that if the type is an open generic type
a `System.NotSupportedException` is thrown instead of a
`System.ArgumentException`.  This fixes
[`Java.InteropTests.JnienvTest.NewOpenGenericTypeThrows()`][3].

Also, `JniBuiltinMarshalers.cs` has some hand-made changes, rendering
it out of sync with `JniBuiltinMarshalers.tt`.  Update
`JniBuiltinMarshalers.tt` appropriately and regenerate it.

[0]: https://docs.oracle.com/javase/specs/jls/se21/html/jls-4.html#jls-4.2.1
[1]: https://github.com/dotnet/java-interop/blob/f30e420a1638dc013302e85dcf76642c10c26832/Documentation/Motivation.md
[2]: https://github.com/dotnet/android/blob/1b1f1452f6b05707418d6605c06e106e6a2a6381/tests/Mono.Android-Tests/Mono.Android-Tests/System.Net/NetworkInterfaces.cs#L107-L137
[3]: https://github.com/dotnet/android/blob/1b1f1452f6b05707418d6605c06e106e6a2a6381/tests/Mono.Android-Tests/Mono.Android-Tests/Java.Interop/JnienvTest.cs#L107-L116