Enable Wind estimator in SITL

[Scavanger]

The SITL "GPS" does not set any velocity data, this is then calculated by the position estimator, but the wind estimator gets its data directly from the GPS. Changed so that the values calculated on demand are used.

[shota3527]

Please have a look at src/main/target/SITL/sim/realFlight.c https://github.com/iNavFlight/inav/commit/4af73a7c85648eb3ba7b14856e11cebfd4dcde32

Actually, i am a little bit skeptical about position estimator's reliability, vibration/offset in accelerometer will cause problems And if using data from pos estimator, the update rate of diffLengthSq will change, and the wind estimator`s filtering/threshold also needs some adjustments