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.
Especially for flaky tests:
- Do objectWillChange.send() _before_ performing the change
- Send more events to .didChange to be more deterministic about test
expectations
Davide