Switch back to Vim

- Change default editor back to vim since doom-emacs is broken at the
  moment
- Conditionally include emacs or vim nix files in configuration.nix
- User username to find dwm-flexipatch path on system
- Add tree and btop to miscellaneous system packages
- Add some cli tools like just and git to home-manager packages
- Add more XDG env vars for config and cache

user/utilities/xdg.nix

@@ -15,6 +15,8 @@
     publicShare = null;
     extraConfig = {
       XDG_GAME_DIR = "${config.home.homeDirectory}/Games";
+      XDG_CONFIG_HOME = "${config.home.homeDirectory}/.config";
+      XDG_CACHE_HOME = "${config.home.homeDirectory}/.cache";
     };
   };
   xdg.mime.enable = true;