[FR]: configure: generate java_library and other Java targets

[alexeagle]

What is the current behavior?

Java is omitted from aspect configure and it's not possible for users to compile it in.

Describe the feature

We could import the extension from bazel-contrib/rules_jvm however it's a Gazelle-Go API implementation and depends on wacky gRPC infrastructure talking to a JVM.

Instead we probably want to use the tree-sitter-java parser, and pass all the same tests as https://github.com/bazel-contrib/rules_jvm/tree/v0.27.0/java/gazelle/testdata but implement the extension in Starlark.

This will also make it possible for users to easily customize the behavior.