refactor(desktop): Don't launch EXWM via Emacs client

Launch EXWM directly in Emacs, instead of first launching an Emacs
server and connecting a client.

In cases where Emacs does not start correctly due to initialisation
errors the error message would never become visible without this change.

desktop.nix

@@ -29,8 +29,7 @@ in {
   services.xserver.windowManager.session = lib.singleton {
     name = "exwm";
     start = ''
-      ${emacs}/bin/emacs --daemon -f exwm-enable
+      ${emacs}/bin/emacs --eval '(progn (server-start) (exwm-enable))'
-      ${emacs}/bin/emacsclient -c
     '';
   };