Services, refactor, clean up, service to automatic

Move service to automatic since it has a separate purpose.

Refactor the default.nix code to include service.nix files so it is
easier to extend code.

nixosModules/services/displaymanager/service.nix

@@ -0,0 +1,23 @@
+{ config, pkgs, lib, ... }:
+
+{
+  options.tuigreet = {
+    enable = lib.mkEnableOption "enables tuigreet with greetd";
+  };
+
+  config = lib.mkIf config.tuigreet.enable {
+    services.greetd = {
+      enable = true;
+      package = pkgs.greetd.tuigreet;
+      settings = {
+        terminal = {
+          vt = 2;
+        };
+        default_session = lib.mkIf config.hyprland.enable {
+          command = "${pkgs.greetd.tuigreet}/bin/tuigreet --time --cmd Hyprland";
+          user = "greeter";
+        };
+      };
+    };
+  };
+}