Factors out notification listening from ForegroundServiceController.

This change introduces the ForegroundServiceNotificationListener
component, which contains the logic formerly in
ForegroundServiceController for updating its state in response to
notification events.  ForegroundServiceNotificationListener adds a
standard NotificationEntryListener to the NotificationEntryManager,
allowing us to remove the explicit calls from NotificationEntryManager;
splitting this out to its own class prevents us from introducing a
circular dependency since NotificationEntryManager still needs to use
the query methods on ForegroundServiceController.

Test: atest SystemUITests, manual
Change-Id: Iec72aa3a9fd90e3f0079db3b2a3c4f1882e59731