index valkyrie work attributes consistent with AF

### Background

Most attributes for Hyrax::Work are defined using `Hyrax::Schema` includes.  A few are defined with `attribute` statements.  Some of these attributes were indexed by ActiveFedora.  Adding in indexing for these to be consistent with ActiveFedora’s indexing.

Indexed in AF, but not in ValkyrieWorkIndexer…
* generic_type_sim
* file_set_ids_ssim

Defined as attribute in Hyrax::Work, but not indexed
* on_behalf_of
* proxy_depositor
* state

Looking for confirmation on how to handle these.

### Related Work

Issue #4487 - Solr docs generated by ActiveFedora and Hyrax::ValkyrieWorkIndexer are not compatible

app/indexers/hyrax/valkyrie_work_indexer.rb

@@ -8,5 +8,37 @@ class ValkyrieWorkIndexer < Hyrax::ValkyrieIndexer
     include Hyrax::PermissionIndexer
     include Hyrax::VisibilityIndexer
     include Hyrax::Indexer(:core_metadata)
+
+    def to_solr # rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity
+      super.tap do |solr_doc|
+        admin_set_label = admin_set_label(resource.admin_set_id)
+        solr_doc['admin_set_sim'] = admin_set_label
+        solr_doc['admin_set_tesim'] = admin_set_label
+        solr_doc['member_ids_ssim'] = resource.member_ids
+        solr_doc['member_of_collections_ssim']    = collection_labels(resource.member_of_collection_ids)
+        solr_doc['member_of_collection_ids_ssim'] = resource.member_of_collection_ids
+
+        # solr_doc['on_behalf_of'] = ''
+        # solr_doc['proxy_depositor'] = ''
+        # solr_doc['state'] = ''
+
+        # solr_doc['generic_type_sim'] = ['Work']
+
+        # This enables us to return a Work when we have a FileSet that matches
+        # the search query.  While at the same time allowing us not to return Collections
+        # when a work in the collection matches the query.
+        # solr_doc['file_set_ids_ssim'] = solr_doc['member_ids_ssim'] # TODO: Doesn't this return child works too?
+      end
+
+      private
+
+      def admin_set_label(id)
+        Hyrax.query_service.find_by(id: id).title
+      end
+
+      def collection_labels(ids)
+        Hyrax.query_service.find_many_by_ids(ids: ids)&.map(&:first_title)
+      end
+    end
   end
 end

spec/indexers/hyrax/valkyrie_work_indexer_spec.rb

@@ -53,4 +53,20 @@ def to_solr
 
     it_behaves_like 'a Work indexer'
   end
+
+  describe '#to_solr' do
+    let(:admin_set_title) { 'An Admin Set' }
+    let(:admin_set) { create(:admin_set, title: admin_set_title) }
+    let(:collection_title) { 'A Collection' }
+    let(:col1) { valkyrie_create(:hyrax_collection, title: collection_title)}
+    let(:work) { valkyrie_create(:hyrax_work, :with_member_works, member_of_collection_ids: [col1.id], admin_set_id: admin_set.id) }
+
+    it 'includes attributes defined outside Hyrax::Schema include' do
+      expect(solr_document.fetch('admin_set_sim')).to eq admin_set_title
+      expect(solr_document.fetch('admin_set_tesim')).to eq admin_set_title
+      expect(solr_document.fetch('member_ids_ssim')).to match_array work.member_ids
+      expect(solr_document.fetch('member_of_collections_ssim')).to match_array [collection_title]
+      expect(solr_document.fetch('member_of_collection_ids_ssim')).to match_array [col1.id]
+    end
+  end
 end