In the `buildAndStoreApnSettings()` function we need to have a way of retrieving the carrier name of the APN being saved as we need that name later for selecting the APN in the list. We need to have a way of retrieving it easily, as we do with other APN properties in the form. Having this field hidden allows us to use the `cs_rilData()` function. Maybe there would be other ways but this is clean IMHO.