post events: show post-related mod actions on post event page.

Show the following actions on the post events page:

* Post bans and unbans
* Post deletions and undeletions
* Thumbnail regenerations and IQDB regenerations
* Favorites moves
* Rating locks and unlocks
* Note locks and unlocks

Fixes #3825: Events/Moderation page for each post should show eventual ban actions

app/policies/post_event_policy.rb

@@ -24,8 +24,13 @@ class PostEventPolicy < ApplicationPolicy
         attr = attr.to_s.gsub("creator", "uploader").to_sym if type == "Post"
         attr = attr.to_s.gsub("creator", "user").to_sym if type in "PostApproval" | "PostDisapproval"
 
-        # XXX ordering by created_at desc is a query planner hack to make Postgres use the right indexes.
-        events.where(model: type.constantize.visible_for_search(attr, user).order(created_at: :desc))
+        if type == "ModAction"
+          # XXX don't apply visible_for_search to mod actions because it's slow and we know all mod actions are visible
+          events.where(model_type: "ModAction")
+        else
+          # XXX ordering by created_at desc is a query planner hack to make Postgres use the right indexes.
+          events.where(model: type.constantize.visible_for_search(attr, user).order(created_at: :desc))
+        end
       end.reduce(:or)
     else
       events