Add regression detection steps for torch-nightly (#1603)
Summary:
Add regression detection feature to the torch-nightly userbenchmark.
The next step will be adding bisection.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1603
Reviewed By: janeyx99
Differential Revision: D45448579
Pulled By: xuzhao9
fbshipit-source-id: 57e3910c8289f14444f2070c0086046e4f84d074
