demo backend decoupled from operators (#66100)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66100
A backend should not directly dependent on ATen operators. The demo backend is changed to that way for testing purpose.
Test Plan: Imported from OSS
Reviewed By: pavithranrao
Differential Revision: D31384614
Pulled By: iseeyuan
fbshipit-source-id: c97f0c4aa12feb1d124f1d7a852e9955a7a2ce42
