Adding Scalar add/mul. (#24447)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24447
Note: This should be landed ONLY after #24259
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24447
Differential Revision: D16846006
Test Plan: Imported from OSS
Pulled By: zafartahirov
fbshipit-source-id: 458fd65279d98cb177ef206240d24dfcbc8d1c1b
