Ground station(QGC) <=> Pi <=> Pixhawk time sync using GPS?

[JulianOes]

In MAVSDK we get the time from PX4 with the message UTM_GLOBAL_POSITION](https://mavlink.io/en/messages/common.html#UTM_GLOBAL_POSITION), also see: https://github.com/mavlink/MAVSDK/commit/ae9ac87fb07ba43b6c17bc4f1b839730a095c599.