Add Altitude Cruise mode

-add new NAVIGATION_STATE_ALTITUDE_VOYAGER
-this mode does require manual control to enter
-but you can disable the manual control loss failsafe to continue
flying in case of manual control loss
-for MC: in throttle and yaw are controlled like in Altitude mode,
the tilt is controlled via integrated rate input (similar to Acro,
but with tilt limit)

Signed-off-by: Silvan Fuhrer <silvan@auterion.com>

src/drivers/osd/atxxxx/atxxxx.cpp

@@ -387,6 +387,10 @@ OSDatxxxx::get_flight_mode(uint8_t nav_state)
 		flight_mode = "ALTITUDE";
 		break;
 
+	case vehicle_status_s::NAVIGATION_STATE_ALTITUDE_CRUISE:
+		flight_mode = "CRUISE";
+		break;
+
 	case vehicle_status_s::NAVIGATION_STATE_POSCTL:
 		flight_mode = "POSITION";
 		break;