Store module preferences in the Profile.userInfo field for atomicity.
Access and modification are dramatically simplified, and synchronization
comes for free.
On the other side, fix provider preferences synchronization by using
viewContext for the CloudKit container.
Fixes#992
Some providers require specific credentials for OpenVPN, different from
account credentials. Update the API index with this information to show
an information footer and possibly a link to the OpenVPN credentials.
Also, fix the OTP footer not appearing on macOS.
Davide