add -aui/-naui flags for undecidable instances

What does this MR do?

This MR adds the -aui and -naui flags to enable or disable the allowance of undecidable instances (required for some functional dependency trickery such as type arithmetic and type level lists).

The aui flag can be found here: https://gitlab.com/clean-and-itasks/base/compiler/-/blob/main/main/compile.icl#L218

Changes to public APIs

It adds the -aui and -naui flags. Later I will make a nitrile patch to expose the flags in nitrile.yml

Author's checklist (required)

• Intermediate commits compile (use git rebase -i main if not)
• Newly added code has a style consistent with the rest of the repository
• Newly added code is documented (guidelines)
• If bugs have been solved, tests have been added (guidelines)
• A changelog entry has been added (guidelines)

Related issues

N/A