[CS] Create ReferenceNotificationsModule.

Almost all SysUI variants include both NotificationsModule and
NotificationRowModule. This CL combines them into a module called
ReferenceNotificationsModule and uses that module everywhere. It also
removes the notifications module from CentralSurfacesModule, and instead
just puts them at the top-level SysUI modules (since notif classes are
used by much more than just CentralSurfaces.java).

This will help the promoted notifications work, because that work will
add additional notification modules that should also be included wherever
the current modules are included.

Bug: 277764509
Test: SysUI compiles
Flag: EXEMPT refactor
Change-Id: I19390e8211ab8410eb40824752faf5dd55c08282