Formalize Connection CallQuality report APIs

Promote Connection#EVENT_CALL_QUALITY_REPORT as well as
Connection#EXTRA_CALL_QUALITY_REPORT into proper system APIs. These are
used by Telephony to send the call quality report from Telephony over to
Telecom which is retreived by CallDiagnosticService.

Bug: 322513691
Bug: 311773409
Test: atest CtsCallDiagnosticService
Change-Id: I06c0cd021d1de3ff54ead59fb7483547599193e3