Add `--output` option to userbenchmark/nvfuser (#1062)
Summary: Pull Request resolved: https://github.com/pytorch/benchmark/pull/1062
Reviewed By: FindHao
Differential Revision: D38216301
Pulled By: xuzhao9
fbshipit-source-id: 5e73b009c626a1a2d557b8ccf49500883f8c16a2
