Add support for alternate dashboard views

[MichaelBurgess]

There are occasions where alternate views are desirable e.g. if I'm sharing an image of a snapshot via socials (e.g. Twitter), do I want the entire dashboard? It might be very large/long and not suitable for a small image that is meant to convey the state of things. In that scenario you may choose to show just the summary cards (especially for a benchmark), or a different view altogether.

We should support alternate views that containers can opt into and users can select those views (initially via query string should suffice for screenshots).

Snapshots must still contain all data and panels, with the ability to display them in the alternate views.