LibWeb: Add AO for 'module map of realm'

This allows you to get the module map for any realm, whether it is a
principal or synthetic realm. We don't yet have the concept of a
synethetic realm, but this puts the groundwork in place for it.

Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp

@@ -286,6 +286,15 @@ void EnvironmentSettingsObject::disallow_further_import_maps()
     verify_cast<Window>(global).set_import_maps_allowed(false);
 }
 
+// https://whatpr.org/html/9893/webappapis.html#concept-realm-module-map
+ModuleMap& module_map_of_realm(JS::Realm& realm)
+{
+    // FIXME: 1. If realm is a principal realm, then return the module map of the environment settings object of realm.
+    // FIXME: 2. Assert: realm is a synthetic realm.
+    // FIXME: 3. Return the module map of the synthetic realm settings object of realm.
+    return principal_realm_settings_object(realm).module_map();
+}
+
 // https://html.spec.whatwg.org/multipage/webappapis.html#concept-incumbent-realm
 // https://whatpr.org/html/9893/b8ea975...df5706b/webappapis.html#concept-incumbent-realm
 JS::Realm& incumbent_realm()

Userland/Libraries/LibWeb/HTML/Scripting/Environments.h

@@ -141,6 +141,7 @@ void prepare_to_run_script(JS::Realm&);
 void clean_up_after_running_script(JS::Realm const&);
 void prepare_to_run_callback(JS::Realm&);
 void clean_up_after_running_callback(JS::Realm const&);
+ModuleMap& module_map_of_realm(JS::Realm&);
 
 EnvironmentSettingsObject& incumbent_settings_object();
 JS::Realm& incumbent_realm();