Move MISSION_STATE read/write from mavlink to navigator and commander

src/modules/navigator/mission.h

@@ -141,6 +141,11 @@ private:
 	bool read_mission_item(const dm_item_t dm_item, bool is_current, int *mission_index,
 			       struct mission_item_s *new_mission_item);
 
+	/**
+	 * Save current offboard mission state to dataman
+	 */
+	void save_offboard_mission_state();
+
 	/**
 	 * Report that a mission item has been reached
 	 */