is_vtol flag in vehicle_status 

Getting rid of the autostart id based checks if the system is a vtol
Fixes #1503

@tumbili please test
This would need to read:
```
control_mode.flag_external_manual_override_ok = (!status.is_rotary_wing && !status.is_vtol);
```
With the reason being that the VTOL controller applies some special logic as well. We might be able to overcome this, but better be prudent and get this tested and merged.