[cs] Null cast to Bool is false, not runtime error. Closes #2725
[java] normalize capitalization for java-lib packages / names. Closes #2213
[cs] filter out compatible Ref<> / Out<> fields. Closes #2711
[java] Allow @:native metadata to declare JNI methods. Closes #2288
[all] failing test
[tests] Remove native_cs.csproj and add to .gitignore