Handle package changes in autofill manager service

Autofill manager service was not observing package changes thus
we did not properly handle the cases of the service being updated,
added, and removed. Handling, additions is needed to properly
support restore from a backup. Fixed a few missing locks.

Test: all autofill CTS tests pass and manually tested update, add,
      and remove of autofill services.

bug:36638606
bug:36978445

Change-Id: Idd47891774ba2a4e562a1952cbb5a048211fd4e3