bench: Add inodeop_bench benchmark

Add new benchmark capable of generating specific inode operations
workloads. Currently, it supports create, delete, move, hardlink and
symlink.

Test: Manual run on cuttlefish and physical device
Bug: 165903680
Signed-off-by: Stefano Duo <stefanoduo@google.com>
Change-Id: Ia47f259b7ccea5fe1665b272c3cbc9ec1bf2eb56