Allow ConnectionService to ask Telecomm for ringback

Cherry picked from branch lmp-preview-dev because checking the changes into master required an API update, whereas the relevant APIs are @hide-ed in the source branch.

Provides a pass-through from the ConnectionService API to Telecomm allowing
a ConnectionService to either play the ringbacks on its own, or ask Telecomm
to play the ringbacks on its behalf.

Bug: 15190301
Change-Id: Ib0f2ce9bf798ec0df0e6d33559174c82de059a94
(cherry picked from commit 20536bc3c4d40fa96306b0319d8313a7437fc702)
5 files changed