Create a framework for apps / users to register entry-points inside the new language selector.
Implement the framework for use with the footer entry-point.
The entry-point features should not be too intertwined with MediaWiki as we might want to move the language selector out of MediaWiki later.
Use the footer entry-point to link to the new preferences. See T415059: Evaluate placement of language display, input and font related user preferences for more details.
More details to follow.

