Add a config param to avoid Python exception checking overheads

[jabraham17]

Adds Python.checkExceptions (on by default), which allows users to turn off the exception checking to avoid overhead.

This PR also includes a few other cleanups and adds a future for #26579

• start_test test/library/packages/Python
• start_test test/library/packages/Python --compopts -scheckExceptions=false
  • this has 1 expected failure of argPassingTest, which tests exceptions

Future work:

• It would be nice to support this as a per-interpreter param as well, but that opens us up to issues with generics and classes. So for now thats a todo/nice-to-have

[Reviewed by @DanilaFe]