Add EventLogTag notification_enqueue isAppProvided

Adds a field indicating that a notification enqueue event was
app-provided, rather than being an enqueue that occurs because of an
internal system server event.

Test: atest NotificationManagerServiceTest
Flag: EventLogTag change
Bug: 341446091
Change-Id: Ife610a3eda30d133ad2eff60135e9f911169f84c