Support any revisionable entity types

Added additional config and field on the settings form to allow selection of any revisionable entity types on the site.

Moving to NR as I cannot really test it due to https://www.drupal.org/project/revision_cleanup/issues/3487627#comment-1... ✨ Optimize for sites with large number of entities. Active . I see some other references to 'nid' so cannot be sure whether this works yet.

See https://git.drupalcode.org/issue/revision_cleanup-3519218/-/blob/3519218...

Until this is implemented for all entity types, the module page should clearly point out, that only nodes are supported so far.
With all entity types that have revision support in core now like Media and Taxonomy terms, revision cleanup may be really important.