implement detached JWS verification

[mistermoe]

Summary

Includes ability to verify a compact JWS with detached content

Usage

Signing

  final did = await DidJwk.create();
  final payload = Uint8List.fromList('hello'.codeUnits);
  final compactJws = await Jws.sign(did: did, payload: payload, detachedPayload: true);

  print('compactJws: $compactJws');

Verification

import 'dart:typed_data';

import 'package:web5/web5.dart';

void main() async {
  final did = await DidJwk.create();
  final payload = Uint8List.fromList('hello'.codeUnits);
  final compactJws = 'eyJhbGciOiJFZERTQSIsImtpZCI6ImRpZDpqd2s6ZXlKcmRIa2lPaUpQUzFBaUxDSmhiR2NpT2lKRlpFUlRRU0lzSW10cFpDSTZJa05EWm5wS1NHRlhiVEpOZFZoeU9WTm9URmxXU1Voa1JEa3pla1pmWlZScFRGQXhTekJLYm1scFMxVWlMQ0pqY25ZaU9pSkZaREkxTlRFNUlpd2llQ0k2SWpsVVExTTFhMjUyYlMxV1VHSjVVM3BmUjNOdU1HUnZOakZCYWtab1pYaHdaVmRvYTJabFFYRldXSE1pZlEjMCJ9..BuGapDpbkU2cmGTK4A4rmvpcyf-O5-GiLjN7CHuEc7GGI-7pbrPUL-2zGQkfvPlqu_YjSFDJuo9lLYOuZaiOCw';

  final decodedJws = Jws.decode(compactJws, detachedPayload: payload);
}

[ethan-tbd]

!!