[NNC] ported over sum and softmax to new scheme (#56775)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/56775
Test Plan: Imported from OSS
Reviewed By: ZolotukhinM
Differential Revision: D28173905
Pulled By: Chillee
fbshipit-source-id: 865ff71e5a428341d7225f534f7093ef2994fe5a
