LibJS: Move intrinsics to the realm

Intrinsics, i.e. mostly constructor and prototype objects, but also
things like empty and new object shape now live on a new heap-allocated
JS::Intrinsics object, thus completing the long journey of taking all
the magic away from the global object.
This represents the Realm's [[Intrinsics]] slot in the spec and matches
its existing [[GlobalObject]] / [[GlobalEnv]] slots in terms of
architecture.

In the majority of cases it should now be possibly to fully allocate a
regular object without the global object existing, and in fact that's
what we do now - the realm is allocated before the global object, and
the intrinsics between both :^)

Userland/Libraries/LibJS/Runtime/IteratorOperations.cpp

@@ -189,7 +189,7 @@ Object* create_iterator_result_object(VM& vm, Value value, bool done)
     auto& realm = *vm.current_realm();
 
     // 1. Let obj be OrdinaryObjectCreate(%Object.prototype%).
-    auto* object = Object::create(realm, realm.global_object().object_prototype());
+    auto* object = Object::create(realm, realm.intrinsics().object_prototype());
 
     // 2. Perform ! CreateDataPropertyOrThrow(obj, "value", value).
     MUST(object->create_data_property_or_throw(vm.names.value, value));