implement an `api.probe()` method

[Adminiuga]

Whenever you have a chance, could you implement something similar to zigpy/zigpy-deconz#101 ?

Essentially I'd like to be able to run await zigpy_zigate.api.ZiGate.probe(serial_port_path, baudrate) and get either a True if radio was detected or False otherwise. Method should swallow all exceptions.
Currently for deconz or EZSP it justs opens the port, issues some command to which it always should get a response and closes the port.

Not sure if anything similar is possible with zigate. Maybe issuing set_raw_command() and if successful then consider the radio is there.

[Hedda]

@doudz Also see similar zigpy/zigpy-cc#35