Fix for inconsistent smart dial database

The issue was caused by a contact's phone number being removed,
but not the entire contact. Since we currently determine a list
of contacts to be updated by querying for a list of all updated
phone numbers, this would incorrectly exclude the aforementioned
modified contact.

* Use the Contact URI instead of the Phone URI when doing this query
to fix the problem

* Add tests for DialerDatabaseHelper update behavior

* Refactor small portions of DialerDatabaseHelper to facilitate
testing

Bug: 24053247
Change-Id: I18a7706ebbfd39fd686dc84bdbb842cc9e9b5e20