Adds requested elements to a Record's show XML.

[bwatson78]

• app/views/catalog/_physical_holding.xml.builder: throws enumerative code into a partial. Also breaks out items into their own element with associative barcode, vol/issue, and status.
• app/views/catalog/_supplemental_link.xml.builder: a partial created for the requested supplemental links addition.
• app/views/catalog/show.xml.builder:
  • Adds the holding type boolean elements.
  • Points to the partial above for the supplemental links.
  • Partializes the holdings elements and also renames them since we are now referring to online resources.
• spec/system/view_show_page_spec.rb: Updates the spec to expect the new elements and structure.

[bwatson78]

XML produced: https://emory-my.sharepoint.com/:u:/g/personal/bwatso9_emory_edu/ETHfgOAiPBNJpyZqAF7pVwEBSHJvwE4yWl_xoEeqnk2vJA?e=0CUkl5