Summary: This stack gets rid of Flippers old sheet abstraction that relies on native (Electron) overlays, and implements it using Ant dialogs instead. Also removes a lot of code by making dialog API imperative, rather than reducer organised, like done in the deeplink handling.
Reviewed By: passy
Differential Revision: D30192001
fbshipit-source-id: 9bca3274bd039207e58f8f9394027515e391671d
89b193b438