Switch to BlockedNumberProvider in N SDK

1. ID in BlockedNumberProvider is of type "long" rather than "int".
2. BlockedNumberProvider doesn't include countryIso, so we need to
   calculate it when needed.
3. ag/850887 will remove STRIPPED_PHONE_NUMBER column and notify
   changes to content.
4. Remove unused code.

Bug: 26453530
Change-Id: I09194052b7d5000d20263efaf622250d4c264ae4