Remove duplication between request/response properties in NetworkEventActor (#37651)

- Remove request/response fields in `NetworkEventActor` which now stores
minimal request metadata needed : `URL`, `method`, `timestamps`, `raw
headers`, `body`.
- Refactor add_request and add_response: `add_request` takes the
incoming DevtoolsHttpRequest and populates
`request_url`, `request_method`, `request_started`,
`request_time_stamp`, `request_body`, `request_headers_raw`
`request_cookies`, `request_headers`,`total_time` and `event_timing`
(via a new helper that computes Timings)
While `add_response` takes the incoming DevtoolsHttpResponse and
populates `response_headers_raw`, `response_body` ,`response_cookies`,
`response_headers`, `response_start`, `response_content`
- Add a call to `resources_updated` to push initial request info in
`handle_network_event`
Testing: Run and logged servo in devtools mode and now, the request
header info isavailable as soon as the request gets initiated
Fixes: https://github.com/servo/servo/issues/37566

---------

Signed-off-by: Uthman Yahaya Baba <uthmanyahayababa@gmail.com>

components/devtools/network_handler.rs

@@ -31,22 +31,30 @@ pub(crate) fn handle_network_event(
     let mut actors = actors.lock().unwrap();
     match network_event {
         NetworkEvent::HttpRequest(httprequest) => {
-            // Scope mutable borrow
-            let event_actor = {
+            let (event_actor, resource_updates) = {
                 let actor = actors.find_mut::<NetworkEventActor>(&netevent_actor_name);
                 actor.add_request(httprequest);
-                actor.event_actor()
+                (actor.event_actor(), actor.resource_updates())
             };
 
             let browsing_context_actor =
                 actors.find::<BrowsingContextActor>(&browsing_context_actor_name);
             for stream in &mut connections {
+                // Notify that a new network event has started
                 browsing_context_actor.resource_array(
                     event_actor.clone(),
                     "network-event".to_string(),
                     ResourceArrayType::Available,
                     stream,
                 );
+
+                // Also push initial resource update (request headers, cookies)
+                browsing_context_actor.resource_array(
+                    resource_updates.clone(),
+                    "network-event".to_string(),
+                    ResourceArrayType::Updated,
+                    stream,
+                );
             }
         },
         NetworkEvent::HttpResponse(httpresponse) => {