Migrate graphical-session services to systemd

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

users/configs/kitty/default.nix

@@ -30,7 +30,7 @@ in
     theme.extraConfig = "${lib.meta.getExe (pkgs.writeShellApplication {
       name = "reload-kitty";
       runtimeInputs = with pkgs; [ procps ];
-      text = "pkill kitty -SIGUSR1";
+      text = "exec pkill kitty -SIGUSR1";
     })} &";
 
     home.persistence."/cache${user.home}".directories = [ "${hmConfig.xdg.relativeCacheHome}/kitty" ];