OptionaldebugOptionalproviderThe apple provider to use, either deviceCheck or appAttest, or appAttestWithDeviceCheckFallback,
defaults to DeviceCheck. appAttest requires iOS 14+ or will fail, appAttestWithDeviceCheckFallback
will use appAttest for iOS14+ and fallback to deviceCheck on devices with ios13 and lower
debug token to use, if any. Defaults to undefined, pre-configure tokens in firebase web console if needed