Implement new definition of IBufferHub

Now allocateBuffer and importBuffer will return BufferTraits description
to client side.

The hidl_handle BufferInfo requires some complex logic to pack and
unpack, which would be part of another CL.

Test: VtsFwkBufferHubV1_0TargetTest (Passed)
Bug: 116681016
Change-Id: Iff99b08360a5de2f300546ffd8e9b215518a83c8