Improve Dialog component to auto close on cancel or on submit
Change logic to determine whether a dialog is using the new component
Convert some files to TS

Create IStateful interface
Use IState interface everywhere
Remove unnecessary @ts-ignore

Move all sheets to render in a new container which uses FullWindowOverlay, which allows rendering above presentation controllers on iOS.

In order to accommodate the requirements of the work on supporting XMPP
authentication on mobile/react-native, make dealing with Dialog a
little more generic and a little easier.

Rename setStateProperties and setStateProperty to assign and set,
respectively. Inspired by Object.assign, _.assign, and _.set.