Move detached buffer off IonBuffer

1/ Migration DetachedBuffer's metadata to use ashmem-based
   BufferHubMetadata.
2/ Avoid import the actual gralloc buffer into the IonBuffer. Instead,
   just store the native_handle_t of the gralloc buffer in DetachedBuffer.
3/ Replace the usage of BufferDescription/NativeBufferHandle with
   BufferTraits/NativeHandleWrapper, as they both depend on
   IonBuffer. Currently dvr::ProdcuerBuffer and dvr::ConsumerBuffer
   are still using BufferDescription/NativeBufferHandle so that we are
   reimplementing them for DetachedBuffer to avoid chaning
   dvr::ProdcuerBuffer and dvr::ConsumerBuffer at this point.

Bug: 112940221
Bug: 112011098
Bug: 70048475
Test: atest buffer_hub-test
Change-Id: I435180ba80a27b0ff35f0d95fcdbc23412978e22