Revise display on artist commentary versions index

- All text fields are now shown in their non-rendered form
-- This allows changes to be highlighted with the diff builder
-- The different fields were labeled and separated for easier discernment
-- Fields are only shown if they have text in either the current or previous versions
- Various changes are also verbalized for easier discovery
- The date and the user columns were combined
-- This is more in line with other indexes, plus it saves on space
- The revert listing was changed to use a thumbnail instead of post ID links
-- This makes it more in line with the post versions index

app/helpers/artist_commentary_versions_helper.rb

@@ -1,5 +0,0 @@
-module ArtistCommentaryVersionsHelper
-  def artist_commentary_versions_listing_type
-    params.dig(:search, :post_id).present? ? :revert : :standard
-  end
-end