initialize method
Allows you to initialize FaceSDK.
config - configuration file for FaceSDK initialization.
Returns bool indicating success of initialization and a nullable InitException.
Implementation
Future<(bool success, InitException? error)> initialize({
  InitConfig? config,
}) async {
  var response = await _bridge.invokeMethod("initialize", [config?.toJson()]);
  var jsonObject = _decode(response);
  bool success = jsonObject["success"];
  var error = jsonObject["error"];
  if (success) await _onInit();
  return (success, InitException.fromJson(error));
}