User input of self-id, operator-id, system etc. info and sending via MAVLink messages to UAS

[friissoren]

Idea received from @tridge.

Add mavlink output support in the opendroneid android receiver app. It would create a bluetooth serial service which a GCS can connect to. The opendroneid receiver app would then send SELF_ID, OPERATOR_ID, SYSTEM and BASIC_ID via MAVLink. It would need to have a screen to enter the details for those packets. The GCS would then forward those packets to the aircraft. The big advantage is this would give users both a view showing their remote ID is working (on the receiver app screen) and also provide the required information using the phones GPS. It would be somewhat similar to what the various "turn your phones GPS into a bluetooth NMEA GPS" apps on the play store, but sending MAVLink OpenDroneID msgs instead of NMEA.