Feature: GPSTime

Implement `gpstime` feature to allow the use of the GPS timestamp plus the timezone information from the `geonames` feature for timestamping of the processed media files. This would enable the use of the GPS time information for timecode synchronization of multiple camera angles in apps like DaVinci Resolve.

Consider adding an additional prefix to the processed files to clearly identify GPS timed media files.

### References

This would be similar to the GoPro Labs GPS timecode implementation inside the camera firmware but with the big difference that `goprox` is timezone aware and as such can correctly set the entire timestamp and not just minutes and seconds - which is problematic at hour and day boundaries.
https://gopro.github.io/labs/control/gpssync/