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/models/artist_commentary_version.rb

@@ -14,4 +14,17 @@ class ArtistCommentaryVersion < ApplicationRecord
     end
     @previous.first
   end
+
+  def self.status_fields
+    {
+      original_title: "OrigTitle",
+      original_description: "OrigDesc",
+      translated_title: "TransTitle",
+      translated_description: "TransDesc",
+    }
+  end
+
+  def unchanged_empty?(field)
+    self[field].strip.empty? && (previous.nil? || previous[field].strip.empty?)
+  end
 end