Fix specs and refactor

The failing spec revealed some inefficiencies and those were addressed
in this commit.

lib/iiif_print.rb

@@ -128,7 +128,7 @@ def self.default_fields_for(_work, fields: config.metadata_fields)
     fields.map do |field|
       Field.new(
         name: field.first,
-        label: Hyrax::Renderers::AttributeRenderer.new(field, nil).label,
+        label: Hyrax::Renderers::AttributeRenderer.new(field.first, nil).label,
         options: field.last
       )
     end

lib/iiif_print/metadata.rb

@@ -27,15 +27,14 @@ def build_metadata
 
     def build_metadata_for_v2
       fields.map do |field|
-        label = Hyrax::Renderers::AttributeRenderer.new(field.label, nil).label
         if field.name == :collection && member_of_collection?
           viewable_collections = Hyrax::CollectionMemberService.run(work, @current_ability)
           next if viewable_collections.empty?
-          { 'label' => label,
+          { 'label' => field.label,
             'value' => make_collection_link(viewable_collections) }
         else
           next if field_is_empty?(field)
-          { 'label' => label,
+          { 'label' => field.label,
             'value' => cast_to_value(field_name: field.name, options: field.options) }
         end
       end.compact

spec/iiif_print/metadata_spec.rb

@@ -3,15 +3,7 @@
 RSpec.describe IiifPrint::Metadata do
   let(:base_url) { "https://my.dev.test" }
   let(:solr_document) { SolrDocument.new(attributes) }
-  let(:fields) do
-    metadata_fields.map do |field|
-      SampleField.new(
-        name: field.first,
-        label: Hyrax::Renderers::AttributeRenderer.new(field, nil).label,
-        options: field.last
-      )
-    end
-  end
+  let(:fields) { IiifPrint.default_fields_for(fields: metadata_fields)}
   let(:metadata_fields) do
     {
       title: {},
@@ -20,8 +12,6 @@
     }
   end
 
-  SampleField = Struct.new(:name, :label, :options, keyword_init: true)
-
   describe ".build_metadata_for" do
     subject(:manifest_metadata) do
       described_class.build_metadata_for(