Publish Meta Box: Defer to 'private' state of post status instead of 'name'
Publish Meta Box: Users without 'publish_posts' can submit to next moderation status

Users without 'publish_posts' now have access to all of the moderation statuses. As such, the "Submit for Review" button needs some amount of flexibility. We allow for this flexibility by referencing a new 'save_next' label, and paying attention to the next moderation status in `_wp_translate_postdata()`