Remove access to pipeline outputs from NotifPipeline.

* Add NotifLiveDataStore which provides access to and observation of pipeline outputs.
* Adds NotifLiveData which is written to by each of the two pipelines, only when active.
* Replaces an instance of NotifPipeline.getShadeListCount() from NotificationsControllerImpl.
* Replaces an entry listener in LightsOutNotifController with an observer on this data store.

Fixes: 205696003
Test: atest NotifLiveDataImplTest NotificationListenerTest DataStoreCoordinatorTest LightsOutNotifControllerTest
Change-Id: I3f190b601bf0f71cb03d155d240268d06049bbf7