* mavlink_messages: remove LOCAL_POSITION_NED_COV stream

* mavlink_messages.cpp: add ODOMETRY stream

* add MAV_ODOM_LP parameter to activate odometry loopback

* EKF2: add vehicle_odometry publisher

* Replace VISION_POSITION_ESTIMATE loopback with ODOMETRY

* LPE: add vehicle_odometry publisher

* set vehicle_odometry local_frame field

* mavlink_messages.cpp: ODOMETRY frame_id depends on MAV_ODOM_LP