[NVIDIA TF] Optimize embedding_lookup_sparse using new grad op [PART 2/3]
Hi @cantonios, would you be able to help review this PR please?
Sequel to https://github.com/tensorflow/tensorflow/pull/60383

(This is a rebased version of https://github.com/benbarsdell/tensorflow/pull/1)

cc @cantonios @nluehr @pjannaty