Informs telecomm when the Phone object requests 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.

Adds support so that, if the Phone object requests that ringback be played
by the application layer on its behalf, we pass that on to Telecomm.

Bug: 15190301
Change-Id: I33b65b55dc4176250dd7ae40f27f3522c5f2e86f
(cherry picked from commit 277011fcc6e34236718c1ebb04c2e0f11e9d857e)
2 files changed