nightly-2024-05-08: feat: add support for u16/i16 (#4985)

# Description

## Problem\*

Resolves https://github.com/noir-lang/noir/issues/4908

## Summary\*

Adds cases for `u16`. `i16` was right there so added at the same time.

## Additional Context



## Documentation\*

Check one:
- [ ] No documentation needed.
- [x] 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: Tom French <15848336+TomAFrench@users.noreply.github.com>