service-channel: Add global shotcuts portal backend client type

The global shortcuts portal backend component lives in
gnome-control-center, and is responsible for preseting the GUI for
managing client provided global shortcuts.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4173>

src/wayland/meta-wayland-x11-interop.c

@@ -99,6 +99,7 @@ x11_interop_filter (const struct wl_client *client,
   MetaServiceClientType allowed_client_types[] = {
     META_SERVICE_CLIENT_TYPE_PORTAL_BACKEND,
     META_SERVICE_CLIENT_TYPE_FILECHOOSER_PORTAL_BACKEND,
+    META_SERVICE_CLIENT_TYPE_GLOBAL_SHORTCUTS_PORTAL_BACKEND,
   };
   size_t i;