Merge branch 'main' into glitch-soc/merge-upstream

Conflicts:
- `app/models/account.rb`:
  Not a real conflict, just upstream getting rid of unused constants too close
  to glitch-soc-specific contents.
  Removed unused constants like upstream did.
- `app/models/trends.rb`:
  Conflict because glitch-soc disabled email notifications for trending links.
  Upstream has refactored this quite a bit and added trending posts.
  Took upstream code, but disabling the extra trending stuff will come in
  another commit.
- `app/views/admin/trends/links/index.html.haml`:
  Conflict due to glitch-soc's theming system.
  Ported upstream changes accordingly.

app/lib/activitypub/activity/announce.rb

@@ -23,8 +23,7 @@ class ActivityPub::Activity::Announce < ActivityPub::Activity
         visibility: visibility_from_audience
       )
 
-      Trends.tags.register(@status)
-      Trends.links.register(@status)
+      Trends.register!(@status)
 
       distribute
     end

app/lib/activitypub/activity/like.rb

@@ -7,6 +7,8 @@ class ActivityPub::Activity::Like < ActivityPub::Activity
     return if original_status.nil? || !original_status.account.local? || delete_arrived_first?(@json['id']) || @account.favourited?(original_status)
 
     favourite = original_status.favourites.create!(account: @account)
+
     NotifyService.new.call(original_status.account, :favourite, favourite)
+    Trends.statuses.register(original_status)
   end
 end