Add ability to override carrier service package

This change introduces a Carrier Service Package override, requiring
MODIFY_PHONE_STATE, ensuring that CTS can export a CarrierService, and
set itself as the carrier service.

The requirement for the application to also be carrier-privileged still
stands, but omits the SIM-certificate-match requirement, instead
allowing carrierConfig based certificates + carrier service package
override as a sufficient gate (which critically need to both be doable
with the CTS Shell permission identity)

Bug: 266904760
Test: Manually tested with a demo CTS build, will be used for Core
      Networking CTS tests
Change-Id: Idcaaff8c9c3ed67b93bc23237de841219a5be7d7