Don't show importer Solid action for non-removable devices
The point of this action is to let you quickly open Gwenview's importer when a new removable device is plugged in. It doesn't make sense to show it for non-removable devices.
For reasons that I don't understand, this doesn't work, and hides the action for all devices, not just removable ones. @bruns, would you be able to help me figure out why?