Rework landing gear logic

- remove deprecated actuator_controls[INDEX_LANDING_GEAR]
- remove dead code in mc rate controller that used to prevent it from being retracted
on the ground (anyway had no effect as it only affected the actuator_control[LANDING_GEAR]
which wasn't sent to the control allocation)
- for VTOLs handle deployment/retraction of landing gear in AUTO  as a MC (retract if
more than 2m above ground, deploy if WP is a landing WP), plus additionally when transition
flight task is called (ALTITUDE mode and higher)
- for FW in AUTO: add logic in FW Position Controller, depending on waypoint type mainly
- manual landing gear settings always come through (a manual command overrides a previous
auto command, and vice-versa)

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

src/modules/fw_path_navigation/FixedwingPositionControl.hpp

@@ -71,6 +71,7 @@
 #include <uORB/Subscription.hpp>
 #include <uORB/SubscriptionCallback.hpp>
 #include <uORB/topics/airspeed_validated.h>
+#include <uORB/topics/landing_gear.h>
 #include <uORB/topics/launch_detection_status.h>
 #include <uORB/topics/manual_control_setpoint.h>
 #include <uORB/topics/npfg_status.h>
@@ -212,6 +213,7 @@ private:
 	uORB::Publication<tecs_status_s> _tecs_status_pub{ORB_ID(tecs_status)};
 	uORB::Publication<launch_detection_status_s> _launch_detection_status_pub{ORB_ID(launch_detection_status)};
 	uORB::PublicationMulti<orbit_status_s> _orbit_status_pub{ORB_ID(orbit_status)};
+	uORB::Publication<landing_gear_s> _landing_gear_pub{ORB_ID(landing_gear)};
 
 	manual_control_setpoint_s _manual_control_setpoint{};
 	position_setpoint_triplet_s _pos_sp_triplet{};
@@ -414,6 +416,9 @@ private:
 	// nonlinear path following guidance - lateral-directional position control
 	NPFG _npfg;
 
+	// LANDING GEAR
+	int8_t _new_landing_gear_position{landing_gear_s::GEAR_KEEP};
+
 	hrt_abstime _time_in_fixed_bank_loiter{0}; // [us]
 	float _min_current_sp_distance_xy{FLT_MAX};
 	float _target_bearing{0.0f}; // [rad]