Add fastrnns benchmark to CI and upload data to scribe (#42030)
Summary:
Run fastrnns benchmark using pytest-benchmark infra, then parse its json format and upload to scribe.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42030
Reviewed By: malfet
Differential Revision: D22970270
Pulled By: wconstab
fbshipit-source-id: 87da9b7ddf741da14b80d20779771d19123be3c5
