show both, files and file infos in acq.media API response

app/serializers/serializable_acquired_media_release.rb

@@ -7,7 +7,17 @@ class SerializableAcquiredMediaRelease < JSONAPI::Serializable::Resource
               :person_title, :person_company, :created_at, :updated_at, :collection_uid, :territory_old, :term_old,
               :applicable_medium_id, :applicable_medium_text, :territory_id, :territory_text, :term_id, :term_text,
               :restriction_id, :restriction_text, :categories, :description, :tag_list
-  
+
+  has_many :file_infos do
+    data do
+      @object.file_infos
+    end
+
+    meta do
+      { count: @object.file_infos.size }
+    end
+  end
+
   has_many :files do
     data do
       @object.files