Add trending links (#16917)

* 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

app/helpers/admin/filter_helper.rb

@@ -6,6 +6,8 @@ module Admin::FilterHelper
     CustomEmojiFilter::KEYS,
     ReportFilter::KEYS,
     TagFilter::KEYS,
+    PreviewCardProviderFilter::KEYS,
+    PreviewCardFilter::KEYS,
     InstanceFilter::KEYS,
     InviteFilter::KEYS,
     RelationshipFilter::KEYS,