Doom Emacs w/ Personal Config

- Update flake.lock
- Add doom emacs nix module to flake
- Change default editor to doom emacs
- Move xdg configuration to a separate file
- Change user home filepaths to use `~`
- Install doom emacs by default
- Add personal doom emacs configuration

user/utilities/default.nix

@@ -7,5 +7,6 @@
     ./file-syncing.nix
     ./keyboard-configuration.nix
     ./passwords.nix
+    ./xdg.nix
   ];
 }