EBookBackendSqliteDB: Fixed an inconsistency in phone number matches.

The phone number national number matching algoritm was hard coding
the country code length to 2, causing some random results.
Tests: Added 3 new contacts and a few more query tests.

The new tests check some specific phone number matching cases
with E_BOOK_QUERY_EQUALS_NATIONAL_NUMBER queries.
Added a utility to deal with phone numbers

This utility can be used to compare phone numbers or to show
how a phone number will be formed and understood according
to a given locale.