nativewindow: Add more benchmarks to evaluate FFI costs

This CL adds two new benchmarks, one for getting an AHardwareBuffer's ID
and another for getting its description.

These should (and do) ultimately take the same amount of time.

Test: just adding new tests
Merged-In: I5e09a2736ab829ca465aaa4073b439a605d49b5a
Change-Id: I7ee6dd4e989c85fe18221f51a998ae1c25221800