FEATURE: Allow recovery of deleted small action posts (PR #14643)

Previously when clicking the Delete button for small action posts there was no way to recover this post if the action was accidental. Now if canRecover is true on the post, which it is just after it is deleted and the post is fetched from the server again, we show an undo button which calls the recover endpoint for the post.

We also now disallow the editing of the post if it is deleted, and show the proper deleted red CSS on the small action post when deleted.