Revamp pipeline view manager

Things are still VERY broken, but this version doesn't crash. Baby
steps.

Starts us down the path towards having a generic view manager that can
handle things besides notification rows.

Simplifies the new interfaces for hiding the NSSL/ENR views even more
and (temporarily) moves them into the NotifViewManager itself.

Test: manual

Change-Id: Iab9152529a87671b49fbb7b1ed41dfec6ef6922f