add dart client to packages

packages/dart_client/test_integration/client_test.dart

@@ -0,0 +1,21 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:logging/logging.dart';
+import 'package:stream_chat/src/client.dart';
+import 'package:stream_chat/stream_chat.dart';
+
+const API_KEY = '6xjf3dex3n7d';
+const TOKEN =
+    'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VyX2lkIjoid2lsZC1icmVlemUtNyJ9.VM2EX1EXOfgqa-bTH_3JzeY0T99ngWzWahSauP3dBMo';
+
+void main() {
+  test('test', () async {
+    final client = Client(
+      '6xjf3dex3n7d',
+      logLevel: Level.INFO,
+      tokenProvider: (_) async => '',
+    );
+    final user = User(id: 'wild-breeze-7');
+
+    await client.setGuestUser(user);
+  });
+}