feat(menu): add menu style options

[cluther]

To allow #{thm_x} styling of menus.

• @catppuccin_menu_style (menu-style)
• @catppuccin_menu_selected_style (menu-selected-style)
• @catppuccin_menu_border_style (menu-border-style)

[vdbe]

This change has some unintended side effects:

• does not work with transparency
  This can be fixed by using bg=default instead of bg=${thm_gray} (maybe also only setting fg have not tested that).
• disabled options are no longer grayed out.
  Don't know how to fix this only other menu option I can find is menu-border-lines (https://github.com/tmux/tmux/blob/master/options-table.c#L332-L366).
  Maybe default to "" and only set when not ""?

Current:

This PR:

[cluther]

Thanks, @vdbe. I'll test those defaults more carefully, and update the pull request.

[cluther]

@vdbe: Switching to bg=default as you suggested works. I can't reproduce the problem with disabled menu options. They do appear disabled for me.

This is with tmux 3.4 installed from nixos-unstable, and configured with catppuccin/nix.
catppuccin-tmux-menu-transparency.webm

[vdbe]

Weird can you try it with just set -g mouse on in the config?

https://github.com/vdbe/catppuccin-tmux-dev

[cluther]

I had mouse enabled. Thanks for the flake. That helped me reproduce the problem. I still don't totally understand why the disabled items were losing styling under that basic config, and not my own, but it was solely related to changing the menu-style value. By explicitly setting it to default the problem goes away. So I set menu-border-style that way as well just to be safe. Setting menu-selected-style to default doesn't work, so I made that as close to the tmux default of bg=yellow,fg=black as I could.

Based on testing with your flake as you showed, this looks good to me now.