Add command palette

[yohannd1]

Attempt to add a command palette to furnace, to potentially facilitate finding specific actions and improve keyboard-only usage.

For more info, see this github discussion and this discord thread.

Right now this is quite an early version, though. Feel free to critique this as the design is still very fluid.

2023-06-15.01-38-46.mp4

Checklist

• Make basic implementation
• Decide on how the window should appear (centered on top like VsCode/Atom? following the mouse?)
• Add submenus
  • Recent files
  • Select instrument
  • Select sample
  • Change instrument in selection
  • Add chip
• Improve display names (some actions do not have a full description)

[freq-mod]

Is it still being worked on?

[yohannd1]

Yes, but kinda slowly. I haven't had much time&motivation to work on this lately.
It's almost finished, though. I think I was just going to rename some actions.

[yohannd1]

Hello! I thought I had finished this around 2 months ago (hence me marking it as ready for review), but I realized I forgot to rename a few things.
So I did that now, along with keeping it up to date with the master branch. Now it's 100% ready for review!

[tildearrow]

You have accidentally changed the fmt submodule...
Please set it to the commit that upstream Furnace uses.

[tildearrow]

Amazing work. Check out these two review comments.

[yohannd1]

Quick fix! Forgot that instrument numbers should be displayed as hexadecimal, so changed it in the code from %02d to %02x.

[tildearrow]

Good job! Will test later, but for now merging.