port at::mul to structured (#52692)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/52692
Porting `at::mul` to structured.
One other issue I hit with the port was the fact that there are a bunch of other places around the code base that used to call out to variants of `at::native::mul`, which no longer exists. *Technically*, `at::cpu::mul` does the equivalent thing now, so I patched most call-sites to use that. There were two other places where I did something slightly different (calling `at::cuda::mul` and `at::mul`, respectively), which I called out in the comments.
Test Plan: Imported from OSS
Reviewed By: ezyang
Differential Revision: D27029822
Pulled By: bdhirsh
fbshipit-source-id: 6cc80de0dfccec304bf8e16a1823e733bed27bf4
