fix: cannot find Scala companion module from Java

To find Scala companion mudule from Java in mixed sources,
we should strip module suffix `$`.
This provides workaround for #17255, but it requires some refinment to fix it
because not-fully-qualified type like the following example still fails
to compile due to missing symbol.

```java
package example;

public class Bar {
    private static final Foo$ MOD = Foo$.MODULE;
}
```

This is because `pre` in `javaFindMember` for `Foo` in the case above is `<root>`,
not `example` and therefore `pre.findMember` looks for `<root>.Foo` instead
of `example.Foo`.

I'm not sure whether the qualifier is intentionally dropped.

References
- #12884
- scala/scala#7671

compiler/src/dotty/tools/dotc/core/ContextOps.scala

@@ -55,11 +55,17 @@ object ContextOps:
     final def javaFindMember(name: Name, pre: Type, lookInCompanion: Boolean, required: FlagSet = EmptyFlags, excluded: FlagSet = EmptyFlags): Denotation =
       assert(ctx.isJava)
       inContext(ctx) {
-
+        import dotty.tools.dotc.core.NameOps.*
         val preSym = pre.typeSymbol
-
         // 1. Try to search in current type and parents.
-        val directSearch = pre.findMember(name, pre, required, excluded)
+        val directSearch =
+          if name.isTypeName && name.endsWith(StdNames.str.MODULE_SUFFIX) then
+            pre.findMember(name.stripModuleClassSuffix, pre, required, excluded) match
+              case NoDenotation => NoDenotation
+              case symDenot: SymDenotation =>
+                symDenot.companionModule.denot
+          else
+            pre.findMember(name, pre, required, excluded)
 
         // 2. Try to search in companion class if current is an object.
         def searchCompanionClass = if lookInCompanion && preSym.is(Flags.Module) then

compiler/test/dotc/pos-test-pickling.blacklist

@@ -29,6 +29,7 @@ i16649-irrefutable.scala
 strict-pattern-bindings-3.0-migration.scala
 i17186b.scala
 i11982a.scala
+i17255
 
 # Tree is huge and blows stack for printing Text
 i7034.scala

tests/pos/i17255/Bar.java

@@ -0,0 +1,6 @@
+package example;
+
+
+public class Bar {
+	private static final example.Foo$ MOD = example.Foo$.MODULE$;
+}

tests/pos/i17255/Foo.scala

@@ -0,0 +1,5 @@
+package example
+
+case class Foo(i: Int)
+
+object Foo