Move NotificationLockscreenUserManager out of NSSL

The NotificationLockscreenUserManager is no longer injected into the
NotificationStackScrollLayout. It is instead supplied to
NotificationStackScrollLayoutController, which registers an
appropriate listener and tells the NSSL when relevant information
changes.

Bug: 147245740
Test: atest SystemUITests
Change-Id: I4a979715e73c1c82bdd2d0759051b7e3c8814a73