This tests all relevant scenarios of device removal, i.e.:
* device is not open
* device is currently closing
* device is open and idle
* device is currently opening
* device is open and active
The test ensures that in all scenarios the following holds true:
* device "removed" signal is only emitted after the action completes
* context "device-removed" signal is only emitted after the device has
been closed
Note that the "opening" case is special. Here we confirm that a success
from "open" will not be overriden by a FP_DEVICE_ERROR_REMOVED error, in
order to correctly signal that the internal device state is open and it
needs to be closed.
