jnimarshalmethod-gen should be used & usable with `Java.Base-Tests`

[jonpryor]

In the same way that jnimarshalmethod-gen is run against Java.Interop.Export-Tests in 77800dd, jnimarshalmethod-gen should also be run against Java.Base-Tests, and Java.Base-Tests should continue passing after the fixup, a'la:

% dotnet test --logger "console;verbosity=detailed" bin/TestDebug-net7.0/Java.Base-Tests.dll &&
    dotnet bin/Debug-net7.0/jnimarshalmethod-gen.dll bin/TestDebug-net7.0/Java.Base-Tests.dll  &&
    dotnet test --logger "console;verbosity=detailed" bin/TestDebug-net7.0/Java.Base-Tests.dll

One problem with this now is that jnimarshalmethod-gen doesn't do anything to Java.Base-Tests.dll, even though it has at least one Java.Lang.Object subclass, and thus requires marshal methods.