Set up ZED-F9T in TIME mode (instead of position)

From the [ZED-F9T's Integration Manual](https://content.u-blox.com/sites/default/files/ZED-F9T-00B_IntegrationManual_%28UBX-19005590%29.pdf):

> **3.1.5.4 Timing receiver position**
>
> Time mode is a special receiver mode where the position of the receiver is known and fixed and only
the time and frequency is calculated using all available satellites. This mode allows for maximum
time accuracy, for single-SV solutions, and also for using the receiver as a stationary reference
station.
>
> In order to use time mode, the receiver's position must be known as exactly as possible. Errors in the
fixed position will translate into time errors depending on the satellite constellation.
>
> The following procedures can be used to initialize the timing receiver position:
>
> - Using built-in survey-in procedure to estimate the position.
> - Entering coordinates independently generated or taken from an accurate position such as a
survey marker

For now, I'm okay with the time from normal GPS position + time mode, as it's extremely stable with my newly-installed outdoor antenna:


But it would be interesting to see if the timing can get closer to the < 5 ns ideal on the ZED-F9T if I can set it to fixed position mode. It seems like the procedure involves:

1. Enable `Survey-in` mode, either for a set period of a few minutes (up to like a day) to acquire an extremely precise position
2. Wait for a precise location to be acquired, and then it should give a `TIME` fix rather than a `3D` fix.
3. Hope the building does not fall over so the antenna stays rigidly in place.

Is it as simple as setting `UBX-CFG-TMODE3` using `ubxtool` or `pygpsclient`? See: [GPSd Survey-in configuration](https://gpsd.io/ubxtool-examples.html#_survey_in_configuration).

Start with section 3.1.5.4 of the ZED-F9T Integration Manual and the gpsd ubxtool survey-in configuration examples linked in the issue. Check how the project currently configures the receiver and whether UBX-CFG-TMODE3 is exposed. Done means the receiver can be placed in fixed-position time mode and reports a TIME fix.

Written by the indexing model from the issue text.