Notify all packages is uid-mode is changed

Multiple packages might share a UID, but appOpsService might not have
cached the uid->package mapping for those yet. Hence the only way to
list all packages for a uid is to ask package manager.

setUidMode already handled this correctly, hence factor out the code
into notifyOpChangedForAllPkgsInUid and reuse it from
commitUidStatePendingLocked.

Bug: 148180766
Test: (on master) atest CtsAppOpsTestCases:android.app.appops.cts.ForegroundModeTest
Change-Id: I99a8f255a60d3523da7eb36a8f2c9426af1a1fea
Merged-In: I2d5d6c7aa38d201707349a137c9c29b7987775be
(cherry picked from commit 29e092bf)