Call establish view

This adds a call establishment view similar to the call offer view (created in part by forking it).  

This doesn't quite complete the card (still need to convert a static element into a view as well as write a functional test).  That said, this stands alone quite nicely: it's well unit-tested, and it works pretty much exactly as one would expect.

Because of this, and because I'd like to avoid conflicts and get reviewed before it gets too big, I'd like to land this now. and finish the remaining bits in a separate PR.