[compiler] moduleTypeProvider support for aliasing signatures (#33526)

This allows us to type things like `nullthrows()` or `identity()`
functions where the return type is polymorphic on the input.

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* #33571
* #33558
* #33547
* #33543
* #33533
* #33532
* #33530
* __->__ #33526
* #33522
* #33518