artists: fix old artists with invalid names.

There are a lot of old artist entries with Japanese names. These names
are now invalid and these artist entries can't be edited because they
fail validation checks.

Add a fix script to delete all artist entries with non-ASCII names, and
rename them to `artist_1234`.

script/fixes/093_fix_invalid_artist_names.rb

@@ -0,0 +1,20 @@
+#!/usr/bin/env ruby
+
+require_relative "base"
+
+with_confirmation do
+  CurrentUser.scoped(User.system) do
+    Artist.where("name ~ '[^[:ascii:]]'").find_each do |artist|
+      artist.other_names += [artist.name]
+      artist.name = "artist_#{artist.id}"
+      artist.is_deleted = true
+      artist.save!
+
+      if artist.saved_changes?
+        puts "id=#{artist.id} oldname=#{artist.name_before_last_save} newname=`#{artist.name}` other_names=#{artist.other_names}"
+      end
+    rescue ActiveRecord::RecordInvalid
+      puts "id=#{artist.id} name=#{artist.name} error=#{artist.errors.full_messages.join}"
+    end
+  end
+end