RegisterExtenders invoked before Init, cannot avoid adding rules to ko.extends.

There is an option to set registerExtenders to false when init is invoked to bypass registerExtenders, but the bootstrap has already executed kv.registerExtenders ( ~ line 914 )

```
//now register all of these!
(function () {
kv.registerExtenders();
}());
```

You cannot avoid registering all the rules as ko.extensions

Start in the bootstrap around line 914, where kv.registerExtenders() is invoked, and trace how the registerExtenders option is handled during init. Confirm the expected initialization order and make the false option prevent the extenders from being registered in ko.extenders; verify the existing validation behavior remains intact.

Written by the indexing model from the issue text.