Add dataverse example for the scientific dataset distribution schema

[jsheunis]

• Source dataset: https://dataverse.nl/dataset.xhtml?persistentId=doi:10.34894/R1TNL8
• Conversion code: https://github.com/jsheunis/datalad-concepts/blob/tools/tools/dataverse_to_distribution.py
• A validation test config is also included, so that validation of this data sample will be included in make check-validation. And the outdated dataverse example data and config in the 'tests' directory have been removed.

TODO:

• include study activity and study participants
• include access
• include funder

[mih]

Merging after rebase, to prep for the next iteration.