LibWeb: Implement Resource Timing

Author: https://github.com/Lubrsi
Commit: 6d1f78198d
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3704
Reviewed-by: https://github.com/ADKaster ✅

Libraries/LibWeb/Fetch/Infrastructure/HTTP/Requests.h

@@ -531,6 +531,7 @@ private:
 
 StringView request_destination_to_string(Request::Destination);
 StringView request_mode_to_string(Request::Mode);
+FlyString initiator_type_to_string(Request::InitiatorType);
 
 Optional<Request::Priority> request_priority_from_string(StringView);