[code-reflection] RFR: BytecodeGenerator, BytecodeLift and TestBytecode improvements

[Adam Sotona]

BytecodeGenerator, BytecodeLift and TestBytecode improvements

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Commit messages:
 - minor fixes
 - TestWhile merged into TestBytecode
 - improving TestBytecode coverage
 - generalized TestBytecode for variable argument count and types
 - Interpreter return types fix + improved TestBytecode and more selective BytecodeLift
 - tests consolidation
 - reorganization of the tests
 - multiple lift tests aggregated into parametrized TestLift + anewarray lift fix
 - BytecodeLift work in progress + new parametrized test
 - BytecodeLift work in progress
 - ... and 12 more: https://git.openjdk.org/babylon/compare/6bc5733d...37e7f7fa

Changes: https://git.openjdk.org/babylon/pull/44/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=44&range=00
  Stats: 3171 lines in 21 files changed: 1172 ins; 1724 del; 275 mod
  Patch: https://git.openjdk.org/babylon/pull/44.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/44/head:pull/44

PR: https://git.openjdk.org/babylon/pull/44