Calculate trends in temporary sets to avoid having to manage items
that go below the decay threshold while not having any moments
where a half-processed set is accessible to end-users
* Add trending statuses
* Fix dangling items with stale scores in localized sets
* Various fixes and improvements
- Change approve_all/reject_all to approve_accounts/reject_accounts
- Change Trends::Query methods to not mutate the original query
- Change Trends::Query#skip to offset
- Change follow recommendations to be refreshed in a transaction
* Add tests for trending statuses filtering behaviour
* Fix not applying filtering scope in controller
* Add trending links
* Add overriding specific links trendability
* Add link type to preview cards and only trend articles
Change trends review notifications from being sent every 5 minutes to being sent every 2 hours
Change threshold from 5 unique accounts to 15 unique accounts
* Fix tests
