Migrate package notification controls to AppOps.

We still show the [X] Show Notifications box in
InstalledAppDetails for now, however the information should
be mostly in sync with the AppOps screen. ("Mostly" because
there's no way to register for changes to AppOp modes at
present.)

Change-Id: Ia5cdda26c140aed8ee7329caaeedac04b8cbd8f1