Improve faulty parsing. Add semantic snippets

[privat]

This PR does 3 related things

• Improve and fortify the parse, doSemanticAnalysis and compile methods of RBCodeSnippet.
  • and improve the related tests.
  • add an onError: version to have a "non-faulty" mode that throws errors.
  • and add the related tests on onError version.
• Teach OCASTTranslator to emit runtime error when trying to assign read-only variable (instead of crashing or corrupting the image).
• Add new snippets related to semantic errors and warnings
  • Some are OK as is, others need fixmes and skips

These change feels the minimal set to have a bunch of new test that pass CI reasonably (with fixme and skips).

For the sake of simplicity (and reviewability). The following is let to future PR:

• Handle semantic error in the AST
• Test semantic warnings (currently, they are just ignored by RBCodeSnippetTest)
• Do something meaningful with backend error (they should be caught at semantic-time!).

[Ducasse]

You look to have a lot of fun and this is super nice to see this :)

[MarcusDenker]

failing test not related: TKTCommonQueueWorkerPoolTest>>testWorkerPoolDoesNotExceedPoolSizeWhenSchedulingTasksInParallel