Otherwise, we potentially work with garbage.

This changes how the found gimbals are referenced. Instead of only using
the gimbal device ID for the gimbal map, we now also use the gimbal
manager compid.

This assumes that it is valid to have more than one gimbal manager with
non-MAVLink gimbals attached, which means the gimbal_device_id would
clash in that case, e.g. both would be 1.

Therefore, we use the gimbal manager compid as well as the associated
gimbal_device_id as the map key.

We should use the new yaw value, not the previous one when calculating
the missing frame.

We shouldn't just send the commands to the vehicle because the gimbal
manager might be implemented on any component, not just the autopilot.