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.

test/unit/note_test.rb

@@ -86,20 +86,6 @@ class NoteTest < ActiveSupport::TestCase
         @post.reload
         assert_not_nil(@post.last_noted_at)
       end
-
-      context "for a note-locked post" do
-        setup do
-          @post.update_attribute(:is_note_locked, true)
-        end
-
-        should "fail" do
-          assert_difference("Note.count", 0) do
-            @note = FactoryBot.build(:note, :post => @post)
-            @note.save
-          end
-          assert_equal(["Post is note locked"], @note.errors.full_messages)
-        end
-      end
     end
 
     context "updating a note" do
@@ -137,17 +123,6 @@ class NoteTest < ActiveSupport::TestCase
         assert_equal(CurrentUser.ip_addr, @note.versions.last.updater_ip_addr.to_s)
       end
 
-      context "for a note-locked post" do
-        setup do
-          @post.update_attribute(:is_note_locked, true)
-        end
-
-        should "fail" do
-          @note.update(x: 500)
-          assert_equal(["Post is note locked"], @note.errors.full_messages)
-        end
-      end
-
       context "without making any changes" do
         should "not create a new version" do
           assert_no_difference("@note.versions.count") do