Improve the microbenchmark framework (#819)
Summary:
This PR reorganizes the nvfuser microbenchmark code to make it easier to add more microbenchmarks.
It moves the `--filters` argument to `nvfuser/__init__.py` since it is benchmark-specific.
It defines a single function, `run(extra_args: List[str])` as the interface.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/819
Reviewed By: davidberard98
Differential Revision: D35082129
Pulled By: xuzhao9
fbshipit-source-id: e7b791758cecbfaeb84da665250202c9495edb25
