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/development/default.nix

@@ -3,5 +3,6 @@
 {
   imports = [
     ./vscode.nix
+    ./doom-emacs.nix
   ];
 }