Add gather embedding module (#4826)

* add gather module

* add gather module

* add test case

* add embedding module

* fix comments

* update embedding module and test case

* refine

* fix comment

* fix comment

* fix comment

Co-authored-by: Xiaoyu Zhang <35585791+BBuf@users.noreply.github.com>
Co-authored-by: BBuf <1182563586@qq.com>
Co-authored-by: oneflow-ci-bot <69100618+oneflow-ci-bot@users.noreply.github.com>