Mock-un-hide the MBMS streaming APIs

In AOSP, this unhid the MBMS streaming APIs and modified the
vendor base classes to no longer pass raw AIDLs to the vendor code.

@hide tags put back in for MR1.

Bug: 30981736
Test: builds
Change-Id: I861e0568e3bf9ee9a937bf6314b1fc839a31f00c
Merged-In: I8dd83d01a7511968ed51a80ad358a48e50c3d1e7
10 files changed