getClientId method
Implementation
@override
Future<String> getClientId() async {
_checkInitialized();
// If we don't have a pub key associated with the seed yet, make one
final Uint8List seed = await _getClientSeed();
final RelayAuthKeyPair keyPair = await relayAuth.generateKeyPair(seed);
return relayAuth.encodeIss(keyPair.publicKeyBytes);
}