* Fix PostgreSQL load when linking in announcements
Fixes#13245 by caching status lookups
Since statuses are supposed to be known already and we only
need their URLs and a few other things, caching them should
be fine.
Since it's only used by announcements so far, there won't
be much statuses to cache.
* Perform status lookup when saving announcements, not when rendering them
* Change EntityCache#status to fetch URLs instead of looking into the database
* Move announcement link lookup to publishing worker
* Address issues pointed out during review
