resume method
Resume any current download, with the pending progress.
Implementation
Future<void> resume() async {
  _isActive();
  if (isDownloading) return;
  _inner = await DownloadFlow.initDownload(_url, _options);
}Resume any current download, with the pending progress.
Future<void> resume() async {
  _isActive();
  if (isDownloading) return;
  _inner = await DownloadFlow.initDownload(_url, _options);
}