Disable invalid menu actions

[LucasPickering]

Description

Describe the change. If there is an associated issue, please include the issue link (e.g. "Closes #xxx"). For UI changes, please also include screenshots.

The implementation is mildly jank, but it's simple and clear to the user. Disabled items can still be selected, they just don't trigger callbacks. This was the easiest thing to implement and I think also the most intuitive.

Closes #222

Known Risks

What issues could potentially go wrong with this change? Is it a breaking change? What have you done to mitigate any potential risks?

The implementation is fairly rigid and also includes some potential O(n^2) code, but in reality n<10 so it's totally fine.

QA

How did you test this?

Added to some unit tests, tested all the actions in the TUI.

Checklist

• Have you read CONTRIBUTING.md already?
• Did you update CHANGELOG.md?
  • Only user-facing changes belong in the changelog. Internal changes such as refactors should only be included if they'll impact users, e.g. via performance improvement.
• Did you remove all TODOs?
  • If there are unresolved issues, please open a follow-on issue and link to it in a comment so future work can be tracked