Add support for VSCode

[sgoudham]

catppuccin/vscode does not have a maintainer that is well versed in Nix anymore. As a result, I would very much appreciate if the maintenance burden of that flake can be moved into here.

I'm presently unsure of the pros and cons of this decision so I would appreciate if someone more inclined with Nix can comment down below what the pros and cons of moving the flake are 👍

Also let me know if this is a bad idea. It feels obvious to me that the flake should be moved but frankly Nix is a bundle of unknowns unknowns to me at the minute.

Thanks in advance as I know @isabelroses @getchoo is doing some preliminary work in order to support this.

[getchoo]

Making this a port request to fit in with other issues 🥴

I think we'll be able to do something like this:

{
  config,
  lib,
  pkgs,
  ...
}:

let
  cfg = config.catppuccin.vscode;
  
  settingsFormat = pkgs.formats.json { };
in

{
  options.catppuccin.vscode = lib.ctp.mkCatppuccinOpt { name = "Visual Studio Code"; } // {
    settings = lib.mkOption {
      type = settingsFormat.type;
      default = { };
      apply = lib.mapAttrs' (name: lib.nameValuePair "catppuccin.${name}");
      description = ''
        Extra extension settings. See https://github.com/catppuccin/vscode?tab=readme-ov-file#catppuccin-settings
        for all options.
      '';
    };
  };

  config = lib.mkIf cfg.enable {
    programs.vscode = {
      extension = [ config.catppuccin.sources.vscode ];
      userSettings = lib.mkMerge [
        {
          "workbench.colorTheme" = "Catppuccin " + lib.ctp.toUpper cfg.flavor;
          "catppuccin.accentColor" = cfg.accent;
        }
        (lib.mkIf (cfg.settings != { }) cfg.settings)
      ];
    }; 
  };
}

This is going to be dependent on #384 though, so putting this in the v2.0.0 milestone as well