Add triton operator benchmark (#2195)
Summary:
Pull Request resolved: https://github.com/pytorch/benchmark/pull/2195
Add a new userbenchmark, `triton`, to benchmark triton/aten/decomposed-aten operators.
Features:
* Reuses `triton.testing.do_bench` function
* Supports `triton.testing.Benchmark`/`triton.testing.do_bench` API to plot benchmark results
* The `regsiter_benchmark` and `register_metric` API to define customized benchmark code and metrics
Reviewed By: jackiexu1992
Differential Revision: D54503920
fbshipit-source-id: 613517e691c7892b97806aed24231fef95929df6
