Auto merge of #10826 - danlrobertson:cookies, r=asajeffrey

Add webdriver commands for (Get|Add)Cookie

Add the webdriver commands for GetCookie and AddCookie. In addition the basic messages for sending cookie data back and forth from the resource thread needed to be created and the handlers for those messages were created as well.

Do we plan to have some sort of test suite for the webdriver at some point? At this point I primarily test my PRs with basic shell scripts with a lot of `curl` and `jq`.

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components/script/dom/document.rs

@@ -1562,7 +1562,7 @@ impl Document {
     }
 
     /// https://html.spec.whatwg.org/multipage/#cookie-averse-document-object
-    fn is_cookie_averse(&self) -> bool {
+    pub fn is_cookie_averse(&self) -> bool {
         self.browsing_context.is_none() || !url_has_network_scheme(&self.url)
     }