[FEATURE] Make license.txt available for restricted access publication.

[Danny-dK]

Is your feature request related to a problem? Please describe.

When a Yoda publication is a restricted access publication, the data is not accessible and only the metadata is shown. The license.txt is part of the data, but as it is a restricted package, it is not viewable (because you can't get to the data where the license.txt resides).

Describe the solution you'd like

Make the license.txtx accessible in either the metadata landing page or separate access to license and data package.

Describe alternatives you've considered

Individuals interested in the license of a restricted package could contact the researcher or support department, but that requires more communication. Another part could be to publish a license openly separately and provide the link to this publication in the restricted access publication metadata (under related resources).

Additional context

Feature request from @DorienHuijser and @nehamoopen

[peer35]

At the VU we created a Template for a custom license text in which the researcher can detail what the data can be used for. It would indeed be great if a visitor could view the contents before deciding if it makes sense to request the dataset.

Another option could be to add a "Rights" text field when a user chooses "Custom" as license. Datacite allows free text in there (https://datacite-metadata-schema.readthedocs.io/en/4.5/properties/rights/)? Then the contents could be shown in the metadata on the landing page.