Add an admin dashboard for managing required rights

There should be a dashboard in the admin area that displays a table (Live Data) of all pages with columns for the enforcement status and the enforced right. There should be an action on every page to change the required rights.

This could be an almost standard LiveTable source except that it currently doesn't support the enforcement status and we can't limit this to pages with the required right class so we would need to support viewing a property from a different class (see XWIKI-22400). An easier option for the implementation is probably a custom LiveTable source.