Indicate errors in CF output in UI

[barbeau]

Summary:
As mentioned in https://forum.xda-developers.com/showpost.php?p=79538493&postcount=245 and shown in https://medium.com/@papylepian/mi-9-9140f7db50da, some devices like the Xiaomi Mi 9 have obviously wrong CF output, like two "L1" signals for the same GNSS.

I'd like to flag this output in the GPSTest UI - perhaps just coloring the font red would be sufficient for a first iteration.

Related to #265 - showing "dual-frequency support" label, as they'll likely share the same internal data structure.

Steps to reproduce:

Look at the CF column on the Xiaomi Mi 9

Expected behavior:

Flag obviously wrong CF output

Observed behavior:

No obvious indication that the data is wrong

Device and Android version:

Xiaomi Mi 9

Screenshots:

See https://medium.com/@papylepian/mi-9-9140f7db50da

[barbeau]

I've started working on logic that can support this at #355.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[barbeau]

Closing this as a duplicate as it will be part of #313