Add DeviceConfig.onPropertiesChangedListener.

Add a listener which replies with an object containing one or many flags
as well as parsing methods. This should replace the previous listener,
but we need to keep the old one around for now because Google Play
services is reliant on it.

Bug: 126414261
Test: atest FrameworksCoreTests:DeviceConfigTest

Change-Id: Ie8d32eced077a8df17be824e94271bd6b15fae3d