Ignore the --xid option when formatting from Nautilus

The --format-device option required the --xid option to be set because under X11 the idea was that GNOME Disks provides a dialog on top of Nautilus. However, the integration wasn't really good because it lacked any progress and error reporting. Under Wayland it was finally completely broken to have GNOME Disks provide a dialog for Nautilus. Instead, we opened the app in the regular way and displayed the dialog there as usual which has the benefit of seeing the job state. Do the same now under X11 by just ignoring the --xid option.

Replaces !38 (closed)