OSD Wind speed in m/s

[Yury-MonZon]

Some of us prefer to see wind speed in m/s, not in km/h. This PR does it: -m/s icon on OSD with corresponding speed in m/s -CLI parameter osd_estimations_wind_mps , OFF by default. -explanation in docs/Settings.md

Enabled only in OSD_UNIT_METRIC mode. Tested in flight (vision font).