Log FGS ENTER event synchronously.

To make sure the ENTER event has correct timestamp and other fields from
ServiceRecord.

Add field mFgsNotificationWasDeferred to save mFgsNotificationDeferred value
when mFgsNotificationDeferred is set true, should look at EXIT
event for fgs_notification_deferred instead of ENTER event.

Bug: 191054441
Test: build and run, monitor westworld event logs.
Test: atest CtsAppTestCases:android.app.cts.NotificationManagerTest
Test: atest CtsAppTestCases:android.app.cts.ServiceTest
Test: atest CtsStatsdAtomHostTestCases:android.cts.statsdatom.statsd.UidAtomTests#testForegroundServiceState
Change-Id: I07ace3810b6bbed4860065e7e06453441794f80c