Receive pkg install/uninstall finish in foregound

The processing of these events only shows a dialog or writes a file to
disk or updates/removes a notification. No expensive processing is done.

On the other hand the user waits for (un)installations to happen.

Bug: 65078751
Test: Installed and uinstalled apps.
Change-Id: I15f59f8ed6b024a193335e68adac84853d8c5ec8
(cherry picked from commit 2983a822)