Centralize MessageBus post updates

After this change, only two files directly publish to MessageBus with a
topic interpolated in the channel: Post and TopicUser.

lib/post_revisor.rb

@@ -21,6 +21,7 @@ class PostRevisor
     @opts = opts
     @new_raw = TextCleaner.normalize_whitespaces(new_raw).strip
 
+    # TODO this is not in a transaction - dangerous!
     return false unless should_revise?
     @post.acting_user = @editor
     revise_post
@@ -30,7 +31,7 @@ class PostRevisor
     update_topic_word_counts
     @post.advance_draft_sequence
     PostAlerter.new.after_save_post(@post)
-    publish_revision
+    @post.publish_change_to_clients! :revised
     BadgeGranter.queue_badge_grant(Badge::Trigger::PostRevision, post: @post)
 
     true
@@ -38,17 +39,6 @@ class PostRevisor
 
   private
 
-  def publish_revision
-    MessageBus.publish("/topic/#{@post.topic_id}",{
-                    id: @post.id,
-                    post_number: @post.post_number,
-                    updated_at: @post.updated_at,
-                    type: "revised"
-                  },
-                  group_ids: @post.topic.secure_group_ids
-    )
-  end
-
   def should_revise?
     @post.raw != @new_raw || @opts[:changed_owner]
   end