LibWeb: Use correct URL parsing methods throughout LibWeb

There are essentially 3 URL parsing AOs defined by the spec:
1. Parse a URL
2. Encoding parse a URL
3. Encoding parse a URL and serialize the result

Further, these are replicated between the Document and the ESO.

This patch defines these methods in accordance with the spec and updates
existing users to invoke the correct method. In places where the correct
method is ambiguous, we use the encoding parser to preserve existing ad-
hoc behavior.

Libraries/LibWeb/HTML/HTMLFormElement.cpp

@@ -222,7 +222,7 @@ WebIDL::ExceptionOr<void> HTMLFormElement::submit_form(GC::Ref<HTMLElement> subm
 
     // 14. Parse a URL given action, relative to the submitter element's node document. If this fails, return.
     // 15. Let parsed action be the resulting URL record.
-    auto parsed_action = document().parse_url(action);
+    auto parsed_action = submitter->document().parse_url(action);
     if (!parsed_action.is_valid()) {
         dbgln("Failed to submit form: Invalid URL: {}", action);
         return {};