add CallControl#setMuteState impl

previously, there was no way to mute a Transactional call via the
CallControl object.  In order to mute the call, the AudioService
was needed.

Now, clients can use CallControl#setMuteState to mute the call.

Fixes: 310669304
Test: 1 new CTS test
Change-Id: I878655c990fc80590339a5d6996f1bf0f9040247
4 files changed