downloadFile method
Implementation
@override
Future<void> downloadFile(SignedFile item) {
final bytes = item.toUInt8List();
final blob = Blob([bytes]);
final url = Url.createObjectUrlFromBlob(blob);
final anchor = AnchorElement(href: url);
anchor.download = item.fileName;
anchor.click();
Url.revokeObjectUrl(url);
return Future.value();
}