oai-pmh mods representation (attempt 2)

[Natkeeran]

This PR provides a MODS representation. This is done by powering a twig powered OAI-PMH Record view powered by a Drupal view consisting of a given Repository Item metadata.

Composer Changes

• places a MODS template (mods.html.twig) via post-update-cmd

Config Changes

• rest_oai_pmh.settings - module config, sets up MODS
• views.view.oai_pmh_item_data - provides the metadata that powers the twig
• search_api.index.default_solr_index - some additional fields such as the ID needed for the above view
• views.view.oai_pmh_item_links - sets up the block needed to show the link
• context.context.display_oai_pmh_item_links - places the block

Note that, All Repository Content OAI-PMH set did not include collection items. I kept it that way. Thus, these links don't show for collection items.

[rosiel]

Just to get a sense of how to talk about this - this template here includes many more fields ("elements") than we currently have the ability to populate with a view. Some will be available to us if we create (e.g) a publisher filter that only shows the publisher. Others might need fields present that are not yet in the metadata profile. But by making a thorough template, we can populate it with whatever data we have and can expand in the future - does that jive with how you envisioned this?

[rosiel]

It's not working for me on the Playbook. The link for MODS uses an "identifier" of oai:http:localhost:8000:node-1, when it needs to be oai:localhost:node-1.

http://localhost:8000/oai/request?identifier=oai%3Ahttp:localhost:8000%3Anode-1&metadataPrefix=mods&verb=GetRecord' http://localhost:8000/oai/request?identifier=oai%3Alocalhost%3Anode-1&metadataPrefix=mods&verb=GetRecord`

I have a pull request coming to fix this.