message: calibration: handle ack for gimbal calibration
  Gimbal calibration is implemented in the "right" way with a long running
  command. This allows us to close the stream when we receive the final
  ACCEPTED ack.
diff: @@ -215,6 +215,11 @@ void CalibrationImpl::calibrate_gimbal_accelerometer_async(const CalibrationCall
  _parent->send_command_async(
  command, [this](MavlinkCommandSender::Result command_result, float progress) {
  command_result_callback(command_result, progress);
  + if (command_result == MavlinkCommandSender::Result::Success) {
  + // The gimbal which implements this so far actually uses acks
  + // with progress and final ack, so we need to finish at the end.
  + report_done();
  + }
  });
  }
  