Java: add class that represents callables that are interesting for MaD models

[jcogs33]

Description

This PR adds a ModelApi class which represents all callables for which we might be interested in having a MaD model. The original purpose of adding this class was to disconnect the manual vs automated coverage counting from the DataFlowTargetApi class since DataFlowTargetApi is too specific to the dataflow model generator.
The ModelApi class will also be useful for replacing some code used in the heuristics queries.
The SrcCallable class may also be useful for TypeFlow.qll.

More specifically, this PR does the following:

• Adds a SrcCallable class with an isEffectivelyPublic predicate in Member.qll to approximate an effectively public callable in Java.
• Creates a new ModelExclusions.qll file to centralize the exclusions needed to identify APIs that are interesting for MaD models, and creates a ModelApi class which uses those exclusions.
• Refactors parts of CaptureModelsSpecific.qll and ExternalApi.qll to use the new ModelExclusions.qll file.
• Updates the GeneratedVsManualCoverage metrics query to use ModelApi instead of DataFlowTargetApi, and adjusts the TopJdkApisTest for this query accordingly.

Consideration

• Any input on better class/predicate/file names and QLDocs is welcome, especially for the following:
  • Anything in Member.qll (Note: the isEffectivelyPublic name was chosen to align with C#'s isEffectivelyPublic predicate name.)
  • Is ModelExclusions.qll a good name or is there something better that can be used?
  • Is ModelApi a good name or is there something better that can be used?
• Test libraries were previously not excluded from the model generator code, but they now will be excluded due to the following line in isUninterestingForModels: c.getDeclaringType() instanceof TestLibrary. Let me know if this exclusion is incorrect for the model generator.
• Should I include a change note for the additions in Member.qll? Or are these trivial enough to not need a change note?

[michaelnebel]

@jcogs33 Thank you for the very good PR description!!!

[michaelnebel]

This looks good to me! Great work Jami!

[jcogs33]

Thanks for the review @michaelnebel! I rebased to get the update from #12851.

@aschackmull When you get a chance, can you review and let me know if you think there should be any changes, especially to Member.qll. 🙏

[aschackmull]

I've adjusted the qldoc a bit. Member.qll LGTM now.

[aschackmull]

• Should I include a change note for the additions in Member.qll? Or are these trivial enough to not need a change note?

No need, I think.