workflows: holdingpen updates

* Adds link to arXiv for arXiv identifiers.

* Shows only INSPIRE categories.

* Change the type of process_record_arxiv workflow
  from 'record' to 'Harvested record' to be distinguished
  from submitted records.

* Adds the type 'Submitted record' to literature and
  literature_simple workflows.

* Adds task halt_to_render to literature_simple workflow
  in order to update the title and description columns in holdingpen
  maintable.

When the workflow is finished (which it is after upload_record_sip) or before running the workflow. `BibWorkflowObject.save()` is called and it sets the `modified = datetime.now()`. So this should happen automatically. We should investigate further on the cache invalidation if it is not.