Show status bar notification on quick navigate from in-call UI

Add logic to force the status bar notification of an outgoing call
to be displayed after a reasonable if the user, e.g. by pressing
Home, navigates away from the in-call UI before it has a chance
to show up.

Bug: 11341599
Change-Id: I13f86b940cc82097596634c7634cb5a8726e7d12