Seperated all config stuff into common nixos modules

modules/nixos/portals.nix

@@ -0,0 +1,8 @@
+{ pkgs, ... }:
+{
+  services.flatpak.enable = true;
+  xdg.portal = {
+    enable = true;
+    extraPortals = [ pkgs.xdg-desktop-portal-gtk pkgs.xdg-desktop-portal-gnome ];
+  };
+}