saveToDirectory method
Saves the file into a directory folder using its current name.
Returns a new AdaptiveFile pointing to the saved file in directoryPath.
Implementation
Future<AdaptiveFile> saveToDirectory(String directoryPath) {
final separator = directoryPath.endsWith('/') || directoryPath.endsWith('\\') ? '' : '/';
return saveTo('$directoryPath$separator$name');
}