java inline expectations proof-of-concept with tests

[ginsbach]

This is a proof-of-concept inline expectations query that I developed alongside the CLI implementation of test postprocessing to verify that everything works and the interface makes sense. It is not meant to be merged, but should serve as inspiration for a proper version.

Note that java/ql/test/query-tests/Postprocessing/passing/SuspiciousRegexpRange.java is an identical copy of java/ql/test/query-tests/security/CWE-020/SuspiciousRegexpRange.java, with the other added (non-empty) .java files being slight variations.