land_detector: multicopter ground contact fixes, improvements, and cleanup

- if "landed" and "maybe_landed" states are false then both the "hit_ground" and the "low_thrust" condition need to be true in order to detect landing
 - ground contact MC NAN setpoint workaround
 - ground contact additionally check acceleration setpoint
 - schedule with vehicle_local_position updates (most updates require valid local position)
 - don't allow LNDMC_Z_VEL_MAX to exceed MPC_LAND_SPEED
 - ground contact horizontal movement checks default to failed if estimates aren't available

src/modules/land_detector/RoverLandDetector.cpp

@@ -44,7 +44,6 @@
 namespace land_detector
 {
 
-
 bool RoverLandDetector::_get_ground_contact_state()
 {
 	return true;
@@ -52,14 +51,11 @@ bool RoverLandDetector::_get_ground_contact_state()
 
 bool RoverLandDetector::_get_landed_state()
 {
-
-	_vehicle_status_sub.update(&_vehicle_status);
-
 	if (_vehicle_status.nav_state == vehicle_status_s::NAVIGATION_STATE_AUTO_LAND) {
 		return true; // If Landing has been requested then say we have landed.
 
 	} else {
-		return !_actuator_armed.armed;  // If we are armed we are not landed.
+		return !_armed;  // If we are armed we are not landed.
 	}
 }