Summary:
Ref T10855. This can't replace the old edit flow yet, but get the basics in place.
(This is actually much closer to just being able to swap than I anticipated since CustomFields sort of just work, but the exiting flow has some "clone existing panel" / "place directly on dashboard" stuff that this doesn't yet.)
Test Plan: Created and edited a panel by manually using the "editpro" flow.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T10855
Differential Revision: https://secure.phabricator.com/D16226
