Fix test - read variable for reproduce KT-3273 fail condition

 #KT-3273 Fixed
Support visibility for protected static members
 #KT-2999 Fixed
Constructor for protected_static nested class should be protected
Rename *.jet -> *.kt in codegen tests
Refactor codegen tests

- initialize environment only once in setUp()
- add comments on why some tests are disabled
- modify and rename some tests
- re-enable now working tests
- extract some tests into files with box()
- remove useless 'throws' declarations and commented code
Remove tests on RTTI

It was never implemented
Refactor codegen tests: no special box() result

box() shall always return "OK"
Remove obsolete special files from android tests
Revert excluding kt344 in SpecialFiles
KT-3277 Exception opening URLClassloader from java SDK. Obviously static class initializer doesn't have a name

EA-43194 - assert: KotlinSignatureInJavaMarkerProvider.getDescriptorForMember

 #KT-3277 fixed