ref(insights): create and use shared domain view header

[DominikB2014]

The header for each domain view is almost identical (as it should be), and now that we've ported most if not all features from the performance landing page, its pretty easy to see the abstraction we can make, and what code we can share here.

This PR makes a shared domain view header and uses it in all views, this makes it much easier to maintain and ensure consistent behaviour.