Name mangling for imported internal declarations (after symbol resolution)

[bamarsha]

This is an alternative to PR #360, part of issue #259. Instead of name mangling as soon as references are loaded (before symbol resolution), name mangling is run just before the syntax tree is built in QsCompilation.Build. The benefit is that it is easier to show specific error messages for inaccessible symbols, instead of an "unknown symbol" message.

Because this happens after symbol resolution, the symbol table needs to be updated to accommodate multiple declarations for a single callable or type if some of them belong to a project/package reference. Thus, the logic for resolving symbols in the symbol table has been refactored so that it is more flexible.

TODO in this PR:

• Allow shadowing imported internal callables
• Allow shadowing imported internal types
• Run name mangling in QsCompilation.Build
• Add tests for name mangling
• Add tests for redeclarations in more than one reference
• Decide what to do about some assertions that were disabled (marked with TODO comments)

TODO in the next PR:

• Allow redeclarations of internal items in more than one reference
• Group internal specializations with the same name in different references correctly

[bettinaheim]

It looks like good progress. I assume the only failing tests are the ones you added for multiple references with the same internal declaration? If so, then I'd suggest to comment those out and make a separate PR that reenables those tests and addresses the remaining two boxes on your todo list.

[bettinaheim]

Looks good. One minor thing related to the test project setup.

[bettinaheim]

Somewhere in this PR you have lost the range information for udts in argument tuples. There is a failing code gen test in the runtime repo.

[bettinaheim]

@MarshallSA Found the issue: The changes here seem to have gotten lost. I'll make a PR to this branch shortly.