transition alignment will force heading now and go to RTL if it cannot reach it in time, handle mission failure correctly, reset after mission update, issue message with actual problem

src/modules/navigator/navigator_main.cpp

@@ -750,3 +750,13 @@ Navigator::publish_att_sp()
 		_att_sp_pub = orb_advertise(ORB_ID(vehicle_attitude_setpoint), &_att_sp);
 	}
 }
+
+void
+Navigator::set_mission_failure(const char* reason)
+{
+	if (!_mission_result.mission_failure) {
+		_mission_result.mission_failure = true;
+		set_mission_result_updated();
+		mavlink_log_critical(_mavlink_fd, "%s", reason);
+	}
+}