Add back privacy chip

This adds back the privacy chip classes (Controller and view).

Change to using Executors and DeviceConfigProxy, also fix tests that
were flaky before.

Test: SystemUITests
Test: enabled hub and see chip appear (after re-opening QS)
Bug: 160966908
Change-Id: Id3e5981a87c33a8cabe7ce348f9512d81ad2b1d8