LibJS: Consistently make prototype the last argument in Object ctors

This is so that we can reliably allocate them in a template function,
e.g. in ordinary_create_from_constructor():

    global_object.heap().allocate<T>(
        global_object, forward<Args>(args)..., *prototype);

The majority of objects already take the prototype as the last argument,
so I updated the ones that didn't.

Userland/Libraries/LibJS/Runtime/StringIterator.h

@@ -17,7 +17,7 @@ class StringIterator final : public Object {
 public:
     static StringIterator* create(GlobalObject&, String string);
 
-    explicit StringIterator(Object& prototype, String string);
+    explicit StringIterator(String string, Object& prototype);
     virtual ~StringIterator() override;
 
     Utf8CodePointIterator& iterator() { return m_iterator; }