Refactor the post preview html to use the ViewComponent framework. This
lets us encapsulate all the HTML, CSS, and helper methods for a UI
component in a single place.
See https://viewcomponent.org.
Remove the nag message when an approver hasn't approved anything
recently. Also remove the modqueue random posts page. As of 3d410398a,
inactive approvers are now warned via dmails.
Standardize on using `show_deleted: true` instead of `tags: "status:any"`
when rendering thumbnails and we want to show deleted thumbnails.
Also fixes it so that deleted thumbnails are shown when reordering pools
and favorite groups.
