VTOL: disable WV when moving

[sfuhrer]

This PR disables weather vane (WV) when moving. Background is that when moving lateral, the roll offset required for this motion also introduces a yawing rate from the WV. This is normally not desired for VTOL when flying in windy conditions, as then the nose of the vehicle gets turned out of the wind, leading to crosswind or tailwind situations.

After this PR, the weather vane would still be active when:

• no stick inputs while flying in manual position controlled mode
• when the velocity setpoint is below half of the mission hover velocity (MPC_XY_CRUISE ), which is typically the case in loiter, takeoff and land situations in auto (mission) mode

In low-wind conditions it it could maybe be desired to have the WV always active in auto mode (like it is now), such that the vehicle automatically yaws in direction of flight. We could thus add a parameter to enable WV in auto mode also when moving. Or instead of making the threshold for WV on/off depending on MC_XY_CRUISE like it is now, making a threshold parameter (which, when set to a high velocity, would always enable WV).
I'm currently rather for the option without another parameter if it can be avoided.

[RomanBapst]

@sfuhrer If this works better for VTOL then I'm fine with bringing it in.

[sfuhrer]

Found an issue with the previous implementation, fixed it and flight tested it again now. No conceptual changes, so I assume you're still okay with that @RomanBapst ?

[codecov]

Codecov Report

Merging #13782 into master will decrease coverage by 0.41%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #13782      +/-   ##
==========================================
- Coverage   36.44%   36.02%   -0.42%     
==========================================
  Files         587      548      -39     
  Lines       49337    47003    -2334     
==========================================
- Hits        17982    16935    -1047     
+ Misses      31355    30068    -1287

Flag	Coverage Δ
#mavsdk	36.02% <0%> (?)
#sitl_mission_FW	?
#sitl_mission_MC_box	?
#sitl_mission_MC_offboard_att	?
#sitl_mission_MC_offboard_pos	?
#sitl_mission_Rover	?
#sitl_mission_VTOL_standard	?
#sitl_mission_VTOL_tailsitter	?
#sitl_python_FW	?
#sitl_python_MC_box	?
#sitl_python_MC_offboard_att	?
#sitl_python_MC_offboard_pos	?
#sitl_python_Rover	?
#sitl_python_VTOL_standard	?
#sitl_python_VTOL_tailsitter	?
#unittest	?

Impacted Files	Coverage Δ
...modules/rover_pos_control/RoverPositionControl.hpp	0% <0%> (-100%)	⬇️
src/modules/land_detector/RoverLandDetector.cpp	0% <0%> (-100%)	⬇️
...fw_pos_control_l1/runway_takeoff/RunwayTakeoff.cpp	6.09% <0%> (-93.91%)	⬇️
...rc/modules/land_detector/FixedwingLandDetector.cpp	0% <0%> (-93.34%)	⬇️
src/lib/mixer/NullMixer/NullMixer.cpp	0% <0%> (-84.62%)	⬇️
src/lib/pid/pid.cpp	0% <0%> (-72.59%)	⬇️
platforms/posix/src/px4/common/lib_crc32.c	0% <0%> (-66.67%)	⬇️
...s/fw_pos_control_l1/runway_takeoff/RunwayTakeoff.h	16.66% <0%> (-66.67%)	⬇️
...modules/rover_pos_control/RoverPositionControl.cpp	0% <0%> (-63.87%)	⬇️
src/modules/land_detector/LandDetector.h	22.22% <0%> (-55.56%)	⬇️
... and 127 more