AirspeedSelector: Only do airspeed scale estimation and airspeed validation with valid GNSS fusion

[sfuhrer]

Compared to GNSS, alternate position observation methods are less accurate and thus generally not good enough to do airspeed validation with. Airspeed validation is thus disabled if no GNSS fusion is happening.

Changelog Entry

For release notes:

Improvement: Only do airspeed scale estimation and airspeed validation with valid GNSS fusion

Alternatives

• Directly fuse GNSS into the airspeed validator (to then be used for wind estimate), instead of using local_position but only if GNSS is fused --> I think this is the way to go, but we then need to figure out how to do signal validation (is using estimator_gps_status.checks_passed enough?).

[bresch]

Ok, yes

[bresch]

but we then need to figure out how to do signal validation (is using estimator_gps_status.checks_passed enough

Yes, this should be enough