[desktop] Refactor into multiple components

roles/desktop/x11.nix

@@ -0,0 +1,19 @@
+{ lib, config, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.roles.desktop;
+in
+{
+  config = mkIf (cfg.enable && cfg.x11) {
+    services.xserver = {
+      enable = true;
+
+      windowManager.i3 = {
+        enable = true;
+        extraPackages = with pkgs; [ dmenu i3status i3lock ];
+      };
+    };
+  };
+}