[Multi-user] Make package changes receiver per-user

Makes the BroadcastReceiver that receives changes to installed packages
and sdcards tied to a specific user.

Bug: 121198607
Test: 1) atest RunBackupFrameworksServicesRoboTests
2) Manual testing with user 0 and 11:
- User started -> receiver registered for correct user;
- Package changed -> correct receiver;
- Package added -> correct receiver, updates bookkeeping for correct user;
- Package removed -> correct receiver, updates bookkeeping for correct user;

Change-Id: I68c034da6ec775a4d0489a2d09fc32854dcf11dc