Improved dataset search and functionality

Add functionality to download an entire dataset. Would probably be best to implement as an API endpoint datasets/{dataset_id}/download in order to be similar to other dowload endpoints. Probably a button in the dataset page?
Similar to entries and materials, we also need a search page + search context for datasets. Should be implementable as a simple aggregation over datasets as was available in v0.9.0. This would allow users to use the existing filters to look for a particular dataset. Currently, users have to first find an entry with a dataset, open the overview and click on the dataset link there.
Possibility to add more detailed documentation for datasets? Instead of a simple comment, maybe we could support a rich text field that could be shown for each dataset?

Edited May 23, 2022 by Lauri Himanen