Add option of 13 to channel position precision

[thebentern]

As a part of the discussion for meshtastic/firmware#4467, @garthvh brought up a good point that the default value of 13 in the iOS app has a legal basis. So I'd like to set that as the default value in the firmware and have that as an option in all of the clients

[b8b8]

Can we get the actual diameter (or radius) in m/km next to each setting as well?

[andrekir]

look like this will keep coming up until we have the full range, so lets do that. the default for MQTT map report is 14 and also not covered. tracking this in #1186