mobileAuthWithOtp
Starts mobile authentication on web by OTP.
Future<String?> mobileAuthWithOtp(String data)
var isSuccess = await Onegini.instance.userClient
    .mobileAuthWithOtp(data)
    .catchError((error) {
        print("OTP Mobile authentication request failed: " + error.message);
    });
if (isSuccess != null && isSuccess.isNotEmpty) {
    print("OTP Mobile authentication request success!");
}