init method
Initializes the multi-language system by reading all JSON files from the directory and subdirectories specified in languagePath.
Returns a Map<String, Map<String, String>>
where the keys are the
filenames (without extensions) and the values are the language
key-value pairs from the JSON files.
Implementation
Future<Map<String, Map<String, String>>> init() async {
final directory = Directory(languagePath);
Map<String, Map<String, String>> result = await _findFiles(directory, {});
return result;
}