Don't hardcode help text: Overmap filter popup

[Kilvoctu]

Summary

SUMMARY: Interface "Don't hardcode help text: Overmap filter popup"

Purpose of change

Help text should not be hardcoded as, if end user changes their keybinds, it will cause discrepancies in the UI.
This PR targets the filter pop up window for the Overmap UI and partially addresses #78986

Describe the solution

Pull the currently set keybind for each command, then replace the help text string with a function that enumerates the keybinds.

Describe alternatives you've considered

A lot of different ways of handling displaying help text. I used the Crafting window implementation as a reference again because it looks clean, even though it has some features that won't be relevant for this popup.

Testing

Game compiles and loads.
Open overmap, open filter popup.
Confirm all filter commands work.
Query something, confirm all search result commands work (previous/next result, confirm, quit, etc.)
Change keybind for TEXT.CLEAR and confirm it updates.

Additional context

This popup is always the same width, regardless of terminal size.

Before

After (looks a little better too, right 🙂)

After changed the keybind for clear