GPS: Configure GPS to give accurate millisecond timing

[ETSells]

Version: v2.7.0

Describe the feature you'd like
It would be helpful to have an accurate timebase for telemetry applications to measure latency (particularly for liquids). We should consider using GPS to give us accurate UTC time, offset it by the UART transmission time, and hold that time internally so we can get the current UTC time as a float with millisecond/10 millisecond accuracy.

Describe alternatives you've considered
It would be very difficult to have an alternate method of syncing a timebase without a half-duplex two-way telemetry protocol.

Additional context
N/A

Points of Contact
Rev 2 Project Lead: @NArmistead
Mod, Driver maintainer; Telemetry & GPS SME: @ETSells

[ETSells]

Note: This has been roadmapped as a potential long-term need for the liquids project. Priority remains at P3 for this release.

[ETSells]

This might require us to switch to the UBX protocol, otherwise we'll need to find a way to compute with millisecond accuracy in software given readings ~80ms apart