Support for API cleanups.

New @SystemApis on Conference and PhoneAccount were missing the required
permissions annotations; add permission enforcement in Telecom.
Renames for various methods/properties in the API surface.

Test: Run Telecom and Telephony CTS tests.
Test: Run Telephony unit tests.
Test: Perform manual single-party-conference regression test to confirm
that conference behavior does not regress.
Bug: 148286830
Bug: 148284863
Bug: 148284843
Bug: 148287068
Bug: 148285484
Bug: 148285560
Change-Id: I1f446d81859fa109d74af3661a42a0bd224de5aa