Multiple research domains on project details page

[pherterich]

DMPRoadmap v.3.1.0 introduces a primary research domain. DMPonline users have queried if this could become a repeatable field going forward to cover interdisciplinary research. Probably a question for @briri to judge feasibility.

[briri]

Yes, this could be converted over to allow for any number of research domains. We would need to:

• Create a new plans_research_domains join table
• Create an upgrade Rake task that moves any old data saved to plans.research_output_id into the new table
• Update the UI to allow multiples (see the links on the edit Org details page for an example of possible implementation)
• Update the v1 JSON output which currently places this information into the Tags array on the RDA Common standard to work with the new table
• Create a ticket to remove the old plans.research_domain_id in a future (after people have had a chance to run the script to migrate existing data)