provide views on dataset landing pages

[saylorsd]

We used to use this but it hasn't been updated since 2016. We can either update it or reimplement it.

I think we can handle this for now using our dataset schema and our theme extension. It's not good to have this behavior spread across two extensions, but in this case we're just adding extra metadata and using it in our bespoke theme so I think we can get to doing it properly later. We could have a hidden metadata field for our packages that indicates what view to show on the landing page. Something like primary_view.