[Junit] Junit support for java debug

[andxu]

[fbricon]

This relates to eclipse-jdtls/eclipse.jdt.ls#172

[ansyral]

1 language server generate and resolve junittest codelens
2 investigate junit interface for invoking a test in commandline
3 customized junit test runner which could run/debug test suites and print test structure and test duration, test status(failure with stacktrace)
4 vscode extension adds commands for junittest run/debug codelens

[ansyral]

eclipse-jdtls/eclipse.jdt.ls#420