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/SyntheticModule.cpp

@@ -148,7 +148,7 @@ ThrowCompletionOr<NonnullRefPtr<Module>> parse_json_module(StringView source_tex
     auto& vm = realm.vm();
 
     // 1. Let jsonParse be realm's intrinsic object named "%JSON.parse%".
-    auto* json_parse = realm.global_object().json_parse_function();
+    auto* json_parse = realm.intrinsics().json_parse_function();
 
     // 2. Let json be ? Call(jsonParse, undefined, « sourceText »).
     auto json = TRY(call(vm, *json_parse, js_undefined(), js_string(realm.vm(), source_text)));