Fixed-wing: split out control of steering wheel into seperate message LandingGearWheel

Completely detach the steering wheel logic from the yaw controller (beside using the
same manual stick input in a manual flight mode).

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

msg/CMakeLists.txt

@@ -109,6 +109,7 @@ set(msg_files
 	IridiumsbdStatus.msg
 	IrlockReport.msg
 	LandingGear.msg
+	LandingGearWheel.msg
 	LandingTargetInnovations.msg
 	LandingTargetPose.msg
 	LedControl.msg

msg/LandingGearWheel.msg

@@ -0,0 +1,3 @@
+uint64 timestamp # time since system start (microseconds)
+
+float32 normalized_wheel_setpoint	# negative is turning left, positive turning right [-1, 1]