The a11y API has never really been picked up by tools vendors, let's
not tie ourselves up here for no good reason.

This unpublishes all css::accessibility, and dependend API.

With that, we can change the rather unfortunately-named add/
removeEventListener to be add/removeAccessibleEventListener, thus
not conflicting with the XComponent methods of the same name.

Change-Id: I595598c3a8e46415f80b2780f333333174865fe4