Define discovery URL for workflows

[csc-felipe]

Proposed solution

The discovery links to study and datasets have so far been using Etsin service, which together with Metax, is part of the Fairdata.

When Metax integration is disabled In workflows without Metax, we need a way to make public links to study and datasets. Datasets can be linked to REMS, but study can't.

Since workflows were introduced in #362 and #596, discovery URL must be defined for different workflows.

Perhaps the workflow schema needs a new field for defining the discovery service there.

• Follow up from Make Metax integration optional #480.

Tasks

• Links for dataset to REMS REMS integration #498
• Links for study

DoD (Definition of Done)

Public links are created for study and datasets when metax integration is disabled.
Public links are created for study and datasets for workflows without metax integration.

Testing

Peer review / manual testing that links work as expected.

[blankdots]

so far our known discovery services are metax/etsin and beacon:

• for FEGA we will still have a metax/etsin URL
• for BigPicture we will have beacon