Draft: lib: Fix "Bluetooth Off/Turn Off" wedged state in gnome-shell

When the adapter was set to be the new default, nothing was telling gnome-shell, which only listens to the "row-changed" signals for updates, that there was a new default adapter, so it was stuck in the off position ("Bluetooth Off" menu header), but rfkill correctly said that a Bluetooth adapter was available and offering to turn it off ("Turn Off").