[Station Locations] Make City field optional

[magicbug]

Discussed in https://github.com/magicbug/Cloudlog/discussions/1538

^{Originally posted by KB2YSI July 18, 2022} Is there a reason that the CITY field in a station location is required?

I frequently operate from many locations, satellite rover, and hardly know what county I am in much less than the town/city. Having to enter that for each location is going to be either completely incorrect or a PITA to obtain the correct name.