session cookie for cross domain websites

By getting the cookie through js, most websites will do cross-domain security processing, so it is basically impossible to get the value of the session, it makes no sense.

Changing the cookie method to the following implementation addresses this issue.

`void getAllCookies(MethodCall call, final MethodChannel.Result result){
String url = call.argument("url");
CookieManager cookieManager = CookieManager.getInstance();
String cookieStr = cookieManager.getCookie(url);
result.success(cookieStr);
}`

Currently making the change locally, will be great to have the fix built into the plugin. See this [article](https://www.programmersought.com/article/4084745977/) for a detailed implementation for iOS and Android.