LibWeb: Use fetch to retrieve all HTMLLinkElement resources

HTMLLinkElement is the final user of Resource/ResourceClient (used for
preloads and icons). This ports these link types to use fetch according
to the spec.

Preloads were particularly goofy because they would be stored in the
ResourceLoader's ad-hoc cache. But this cache was never consulted for
organic loads, thus were never used. There is more work to be done to
use these preloads within fetch, but for now they at least are stored
in fetch's HTTP cache for re-use.

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

@@ -90,18 +90,7 @@ void Request::set_url(URL::URL url)
 // https://fetch.spec.whatwg.org/#request-destination-script-like
 bool Request::destination_is_script_like() const
 {
-    // A request’s destination is script-like if it is "audioworklet", "paintworklet", "script", "serviceworker", "sharedworker", or "worker".
-    static constexpr Array script_like_destinations = {
-        Destination::AudioWorklet,
-        Destination::PaintWorklet,
-        Destination::Script,
-        Destination::ServiceWorker,
-        Destination::SharedWorker,
-        Destination::Worker,
-    };
-    return any_of(script_like_destinations, [this](auto destination) {
-        return m_destination == destination;
-    });
+    return m_destination.has_value() && Infrastructure::destination_is_script_like(*m_destination);
 }
 
 // https://fetch.spec.whatwg.org/#subresource-request
@@ -452,6 +441,76 @@ StringView request_destination_to_string(Request::Destination destination)
     VERIFY_NOT_REACHED();
 }
 
+// https://fetch.spec.whatwg.org/#concept-potential-destination-translate
+Optional<Request::Destination> translate_potential_destination(StringView potential_destination)
+{
+    // 1. If potentialDestination is "fetch", then return the empty string.
+    if (potential_destination == "fetch"sv)
+        return {};
+
+    // 2. Assert: potentialDestination is a destination.
+    // 3. Return potentialDestination.
+    if (potential_destination == "audio"sv)
+        return Request::Destination::Audio;
+    if (potential_destination == "audioworklet"sv)
+        return Request::Destination::AudioWorklet;
+    if (potential_destination == "document"sv)
+        return Request::Destination::Document;
+    if (potential_destination == "embed"sv)
+        return Request::Destination::Embed;
+    if (potential_destination == "font"sv)
+        return Request::Destination::Font;
+    if (potential_destination == "frame"sv)
+        return Request::Destination::Frame;
+    if (potential_destination == "iframe"sv)
+        return Request::Destination::IFrame;
+    if (potential_destination == "image"sv)
+        return Request::Destination::Image;
+    if (potential_destination == "json"sv)
+        return Request::Destination::JSON;
+    if (potential_destination == "manifest"sv)
+        return Request::Destination::Manifest;
+    if (potential_destination == "object"sv)
+        return Request::Destination::Object;
+    if (potential_destination == "paintworklet"sv)
+        return Request::Destination::PaintWorklet;
+    if (potential_destination == "report"sv)
+        return Request::Destination::Report;
+    if (potential_destination == "script"sv)
+        return Request::Destination::Script;
+    if (potential_destination == "serviceworker"sv)
+        return Request::Destination::ServiceWorker;
+    if (potential_destination == "sharedworker"sv)
+        return Request::Destination::SharedWorker;
+    if (potential_destination == "style"sv)
+        return Request::Destination::Style;
+    if (potential_destination == "track"sv)
+        return Request::Destination::Track;
+    if (potential_destination == "video"sv)
+        return Request::Destination::Video;
+    if (potential_destination == "webidentity"sv)
+        return Request::Destination::WebIdentity;
+    if (potential_destination == "worker"sv)
+        return Request::Destination::Worker;
+    if (potential_destination == "xslt"sv)
+        return Request::Destination::XSLT;
+    VERIFY_NOT_REACHED();
+}
+
+// https://fetch.spec.whatwg.org/#request-destination-script-like
+bool destination_is_script_like(Request::Destination destination)
+{
+    // A request’s destination is script-like if it is "audioworklet", "paintworklet", "script", "serviceworker",
+    // "sharedworker", or "worker".
+    return first_is_one_of(destination,
+        Request::Destination::AudioWorklet,
+        Request::Destination::PaintWorklet,
+        Request::Destination::Script,
+        Request::Destination::ServiceWorker,
+        Request::Destination::SharedWorker,
+        Request::Destination::Worker);
+}
+
 StringView request_mode_to_string(Request::Mode mode)
 {
     switch (mode) {