Rework artist versions index view

- Added a changes column explicitly listing all of the changes
-- This makes it more in line with the other version views now
- Does a symmetric difference on the array fields to detect changes

app/models/artist_version.rb

@@ -29,4 +29,41 @@ class ArtistVersion < ApplicationRecord
     end
     @previous.first
   end
+
+  def self.status_fields
+    {
+      name: "Renamed",
+      urls_changed: "URLs",
+      other_names_changed: "OtherNames",
+      group_name: "GroupName",
+      was_deleted: "Deleted",
+      was_undeleted: "Undeleted",
+      was_banned: "Banned",
+      was_unbanned: "Unbanned",
+    }
+  end
+
+  def other_names_changed
+    ((other_names - previous.other_names) | (previous.other_names - other_names)).length > 0
+  end
+
+  def urls_changed
+    ((urls - previous.urls) | (previous.urls - urls)).length > 0
+  end
+
+  def was_deleted
+    !is_active && previous.is_active
+  end
+
+  def was_undeleted
+    is_active && !previous.is_active
+  end
+
+  def was_banned
+    is_banned && !previous.is_banned
+  end
+
+  def was_unbanned
+    !is_banned && previous.is_banned
+  end
 end