posts: remove rating, note, and status locks.

Remove the ability for users to lock ratings, note, and post statuses.

Historically the majority of locked posts were from 10+ years ago when
certain users habitually locked ratings and notes on every post they
touched for no reason. Nowadays most posts have been unlocked. Only a
handful of locked posts are left, none of which deserve to be locked.

The is_rating_locked, is_note_locked, and is_status_locked columns still
exist in the database, but aren't used.

app/models/post_appeal.rb

@@ -31,7 +31,7 @@ class PostAppeal < ApplicationRecord
   end
 
   def validate_post_is_appealable
-    errors.add(:post, "cannot be appealed") if post.is_status_locked? || !post.is_appealable?
+    errors.add(:post, "cannot be appealed") if !post.is_appealable?
   end
 
   def self.available_includes