Fix binder error when an app has many channels

By using a ParceledListSlice when sending the data
between processes.

Test: PreferencesHelperTest
Test: NotificationListenersTest (new since last attempt to land)
Test: NotificationManagerServiceTest
Test: view the notification settings page for an app with hundreds of
notification channels
Bug: 215072888

Change-Id: Iac1ba92b6636e86cf506f1ab3c12dcf803101322