🚧 WIP to work with Valkyrie objects

Changed the #iiif_print_config? to a class_attribute so we don't have to
instantiate the object to check if it's configured.  Added a next to the
indexer so if a curation concern does not have IIIF Print configured,
then we won't index the SetChildFlag onto it.

app/indexers/concerns/iiif_print/child_indexer.rb

@@ -13,6 +13,8 @@ def self.decorate_work_types!
       #
 
       Hyrax.config.curation_concerns.each do |work_type|
+        next unless work_type.respond_to?(:iiif_print_config)
+
         work_type.send(:include, IiifPrint::SetChildFlag) unless work_type.included_modules.include?(IiifPrint::SetChildFlag)
         indexer = work_type.indexer
         unless indexer.respond_to?(:iiif_print_lineage_service)

lib/iiif_print.rb

@@ -129,8 +129,10 @@ def self.grandparent_for(file_set)
   #       an alternative splitting method to create new filesets on the existing work instead of new child works.
   def self.model_configuration(**kwargs)
     Module.new do
-      def iiif_print_config?
-        true
+      extend ActiveSupport::Concern
+
+      included do
+        class_attribute :iiif_print_config, default: true
       end
 
       # We don't know what you may want in your configuration, but from this gems implementation,