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/flight_mode_manager/tasks/Descend/FlightTaskDescend.cpp

@@ -36,6 +36,13 @@
 
 #include "FlightTaskDescend.hpp"
 
+bool FlightTaskDescend::activate(const trajectory_setpoint_s &last_setpoint)
+{
+	bool ret = FlightTask::activate(last_setpoint);
+	_gear.landing_gear = landing_gear_s::GEAR_DOWN;
+	return ret;
+}
+
 bool FlightTaskDescend::update()
 {
 	bool ret = FlightTask::update();

src/modules/flight_mode_manager/tasks/Descend/FlightTaskDescend.hpp

@@ -49,6 +49,7 @@ public:
 	virtual ~FlightTaskDescend() = default;
 
 	bool update() override;
+	bool activate(const trajectory_setpoint_s &last_setpoint) override;
 
 private:
 	Sticks _sticks{this};