System time is not synchronised with accurate time sources via autopilot

The system time on the computer running BlueOs is synchronized via ntp when an internet connection is available. When not connected to the internet it will synchronize with a ground station computer that loads the web interface via the `set_time` api endpoint. However, in use cases with no internet connection or where the web interface is not typically loaded, the system time will not be synchronized. Ideally if the connected autopilot has an accurate time source (GPS) then the system time should be synchronized with the autopilot.

There are mechanisms in the MAVLINK protocol to enable this (`SYSTEM_TIME` and `TIMESYNC`).

Relevant links:
https://mavlink.io/en/services/timesync.html
https://ardupilot.org/dev/docs/ros-timesync.html
https://discuss.bluerobotics.com/t/time-syncronisation-mechanisms-in-blueos/22020

Start by tracing the existing set_time API path and how BlueOS communicates with the connected autopilot. Read the MAVLink SYSTEM_TIME and TIMESYNC documentation linked in the issue, then determine how synchronization should work without internet access or web-interface use. Done means the system time can be synchronized from an accurate autopilot time source.

Written by the indexing model from the issue text.