forum: add /forum_topic_visits.{json,xml} endpoint.

For debugging purposes only.

app/models/forum_topic_visit.rb

@@ -5,4 +5,10 @@ class ForumTopicVisit < ApplicationRecord
   def self.prune!(user)
     where("user_id = ? and last_read_at < ?", user.id, user.last_forum_read_at).delete_all
   end
+
+  def self.search(params)
+    q = super
+    q = q.search_attributes(params, :user, :forum_topic_id, :last_read_at)
+    q.apply_default_order(params)
+  end
 end