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/LibWeb/WebAssembly/WebAssemblyMemoryConstructor.cpp

@@ -13,7 +13,7 @@
 namespace Web::Bindings {
 
 WebAssemblyMemoryConstructor::WebAssemblyMemoryConstructor(JS::Realm& realm)
-    : NativeFunction(*realm.global_object().function_prototype())
+    : NativeFunction(*realm.intrinsics().function_prototype())
 {
 }