feat(nixos): enable USB auto-mounting with udiskie

- Enable udisks2 service
- Enable udiskie via Home Manager

home/modules/graphical/udiskie.nix

@@ -0,0 +1,12 @@
+{ pkgs, ... }:
+
+{
+  services.udiskie = {
+    enable = true;
+    settings = {
+      programs_options = {
+        file_manager = "${pkgs.xfce.thunar}/bin/thunar";
+      };
+    };
+  };
+}