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/Array.cpp

@@ -27,7 +27,7 @@ ThrowCompletionOr<Array*> Array::create(Realm& realm, u64 length, Object* protot
 
     // 2. If proto is not present, set proto to %Array.prototype%.
     if (!prototype)
-        prototype = realm.global_object().array_prototype();
+        prototype = realm.intrinsics().array_prototype();
 
     // 3. Let A be MakeBasicObject(« [[Prototype]], [[Extensible]] »).
     // 4. Set A.[[Prototype]] to proto.