FEATURE: New 'Reviewable' model to make reviewable items generic

Includes support for flags, reviewable users and queued posts, with REST API
backwards compatibility.

Co-Authored-By: romanrizzi <romanalejandro@gmail.com>
Co-Authored-By: jjaffeux <j.jaffeux@gmail.com>

app/serializers/current_user_serializer.rb

@@ -8,7 +8,6 @@ class CurrentUserSerializer < BasicUserSerializer
              :read_first_notification?,
              :admin?,
              :notification_channel_position,
-             :site_flagged_posts_count,
              :moderator?,
              :staff?,
              :title,
@@ -30,8 +29,7 @@ class CurrentUserSerializer < BasicUserSerializer
              :muted_category_ids,
              :dismissed_banner_key,
              :is_anonymous,
-             :post_queue_new_count,
-             :show_queued_posts,
+             :reviewable_count,
              :read_faq,
              :automatically_unpin_topics,
              :mailing_list_mode,
@@ -58,10 +56,6 @@ class CurrentUserSerializer < BasicUserSerializer
     scope.can_create_topic?(nil)
   end
 
-  def include_site_flagged_posts_count?
-    object.staff?
-  end
-
   def read_faq
     object.user_stat.read_faq?
   end
@@ -106,10 +100,6 @@ class CurrentUserSerializer < BasicUserSerializer
     object.user_option.redirected_to_top
   end
 
-  def site_flagged_posts_count
-    PostAction.flagged_posts_count
-  end
-
   def can_send_private_email_messages
     scope.can_send_private_messages_to_email?
   end
@@ -189,20 +179,8 @@ class CurrentUserSerializer < BasicUserSerializer
     object.anonymous?
   end
 
-  def post_queue_new_count
-    QueuedPost.new_count
-  end
-
-  def include_post_queue_new_count?
-    object.staff?
-  end
-
-  def show_queued_posts
-    true
-  end
-
-  def include_show_queued_posts?
-    object.staff? && (NewPostManager.queue_enabled? || QueuedPost.new_count > 0)
+  def reviewable_count
+    Reviewable.list_for(object).count
   end
 
   def mailing_list_mode