APIs for SIM call manager voice status

This CL creates two new PhoneAccount capabilities for the SIM call
manager (and potentially telephony itself for PSTN PhoneAccounts) to
advertise that they support voice calling, potentially independent of
voice service state. With this information, telecom will feed updated
back into telephony for plumbing through the standard ServiceState-based
APIs.

Bug: 205737545
Test: atest android.telecom.cts.PhoneAccountOperationsTest
  (an additional CTS test for the TelephonyManager API will be added as
  a follow-up)
Change-Id: If7a5b03a7aa630823ac238ef27721e5e6cc596e6