Fix missing metadata in IIIF manifest

The default list of manifest metadata fields is sourced from the WorkForm and does not contain the solr field suffix. The delegation in IiifManifestPresenter makes those fields available by method call.

app/presenters/hyrax/iiif_manifest_presenter.rb

@@ -77,7 +77,7 @@ def manifest_metadata
       metadata_fields.map do |field_name|
         {
           'label' => I18n.t("simple_form.labels.defaults.#{field_name}"),
-          'value' => Array(self[field_name]).map { |value| scrub(value.to_s) }
+          'value' => Array(send(field_name)).map { |value| scrub(value.to_s) }
         }
       end
     end