workflows: OAI-PMH production sync

* Adds a new OAI-PMH production sync workflow for use to
  harvest from an Invenio instance.

* Adds configuration of the new OAI-PMH harvest.

* Adds back sample OAI-PMH harvest for harvesting ph-math from
  arXiv.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>