LibJS+LibWeb: Replace GlobalObject with Realm in initialize() functions

This is a continuation of the previous commit.

Calling initialize() is the first thing that's done after allocating a
cell on the JS heap - and in the common case of allocating an object,
that's where properties are assigned and intrinsics occasionally
accessed.
Since those are supposed to live on the realm eventually, this is
another step into that direction.

Userland/Libraries/LibJS/Runtime/ModuleNamespaceObject.h

@@ -31,7 +31,7 @@ public:
     virtual ThrowCompletionOr<bool> internal_set(PropertyKey const&, Value value, Value receiver) override;
     virtual ThrowCompletionOr<bool> internal_delete(PropertyKey const&) override;
     virtual ThrowCompletionOr<MarkedVector<Value>> internal_own_property_keys() const override;
-    virtual void initialize(GlobalObject& object) override;
+    virtual void initialize(Realm&) override;
 
 private:
     // FIXME: UHHH how do we want to store this to avoid cycles but be safe??