Delete spawned child works as a work is deleted

This plugs into the cleanup file sets process, to add additional
cleanup of child works which were created as part of a IiifPrint PDF
split. Other child works are not affected.

app/actors/iiif_print/actors/cleanup_file_sets_actor_decorator.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+# override Hyrax to remove splitting upon work delete
+module IiifPrint
+  module Actors
+    # Responsible for removing FileSets related to the given curation concern.
+    module CleanupFileSetsActorDecorator
+      # @param [Hyrax::Actors::Environment] env
+      # @return [Boolean] true if destroy was successful
+      def destroy(env)
+        file_sets = env.curation_concern.file_sets
+        file_sets.each do |file_set|
+          # we destroy the children before the file_set, because we need the parent relationship
+          IiifPrint::SplitPdfs::DestroyPdfChildWorksService.conditionally_destroy_spawned_children_of(
+              file_set: file_set, 
+              work: env.curation_concern
+              )
+        end
+        # and now back to your regularly scheduled programming
+        super
+      end
+    end
+  end
+end

lib/iiif_print/engine.rb

@@ -52,6 +52,7 @@ class Engine < ::Rails::Engine
       ::BlacklightIiifSearch::IiifSearchAnnotation.prepend(IiifPrint::BlacklightIiifSearch::AnnotationDecorator)
       ::BlacklightIiifSearch::IiifSearch.prepend(IiifPrint::IiifSearchDecorator)
       Hyrax::Actors::FileSetActor.prepend(IiifPrint::Actors::FileSetActorDecorator)
+      Hyrax::Actors::CleanupFileSetsActor.prepend(IiifPrint::Actors::CleanupFileSetsActorDecorator)
 
       Hyrax.config do |config|
         config.callback.set(:after_create_fileset) do |file_set, user|