chore: adding name shadowing tests template program (#4799)

# Description

## Problem\*

Resolves #4672

## Summary\*

The plan is to generate variations of a test program that checks for
several types of name shadowing, and then ensure that we get expected
results or errors for different combinations of name conflicts.

## Additional Context



## Documentation\*

Check one:
- [x] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[For Experimental Features]** Documentation to be submitted in a
separate PR.

# PR Checklist\*

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

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Co-authored-by: jfecher <[email protected]>
Co-authored-by: Tom French <[email protected]>
Co-authored-by: Tom French <[email protected]>