Introduce ControllerCallbackLink

In order to avoid direct AIDL usages in framework, this CL introduces a
new public class ControllerCallbackLink which can prevent usages of
ISessionControllerCallback.

Bug: 122337578
Test: make update-api -j / make -j
      atest CtsMediaTestCases:android.media.cts.MediaSessionTest
      atest CtsMediaTestCases:android.media.cts.MediaControllerTest
Change-Id: Id674576aa071b7fdbd0082bf6189fef2af2d919b