Add BufferTraits to bufferhub interface

IBufferHub will now also returning BufferTraits on allocateBuffer and
importBuffer. BufferTraits contains the information of the underlying
buffer, and could be used to build the actually "remote" buffer object
in client side.

Remove @llndk in documents as it does not make sense (no one else in
android code base seems like using it).

Rewrite VtsHalBufferHubV1_0TargetTest to fit in the interface.

Test: VtsHalBufferHubV1_0TargetTest (passed)
Bug: 116681016
Change-Id: Ic00cffa35903260e5697563cf207bfd62aa589d4