getServerTime method
获取服务器当前时间
注意: web不支持该接口
Implementation
Future<V2TimValueCallback<int>> getServerTime() async {
  if (kIsWeb) {
    return TencentCloudChatSdkPlatform.instance.getServerTime();
  }
  int serverTime = TIMManager.instance.getServerTime();
  return V2TimValueCallback<int>.fromObject(serverTime);
}