Allow telephony test to access hidden connectivity methods

Add lib to telephonytests to provide hidden connectiviy
methods accessibility.

Bug: 182859030
Test: 1. remove framework-connectivity.impl from framework bp ;
      2. cd frameworks/opt/telephony/tests/telephonytests ; mm
Change-Id: I1e7f0d808cc44acb6cf12956bfcbe92ac41b2eac