recognizeByFile method
MRZ detection.
file - path to the file.
Returns a List of List<MrzLine>.
Implementation
Future<List<List<MrzLine>>?> recognizeByFile(String file) async {
  if (_recognizer != null) {
    List<dynamic> results =
        await handleThenable(_recognizer!.recognize(file));
    return _resultWrapper(results);
  }
  return [];
}