Summary:
Remove logout menu item and buttons, turn Link External Account to Add Account
Onboarding window starts hidden, is shown when react component is mounted and sized
Use get/setBounds to animate position and size at the same time smoothly
Fix specs, change 401 notice
Delay bouncing to Gmail to show users the Gmail screen momentarily
Make the animated resizing code defer so it doesn't run in a hard loop, and other animations can run at the same time
Bring back crossfade between screens, remove left/right shift on welcome screens
Test Plan: Run tests
Reviewers: drew, evan
Reviewed By: evan
Maniphest Tasks: T3529
Differential Revision: https://phab.nylas.com/D2054