Collect instruction counts (and wall times) for CI (#55428)
Summary:
This PR add a `--mode` flag and a script to collect microbenchmarks in a single JSON file. I also added a version check since benchmarks are expected to evolve; this also turned up a determinism bug in `init_from_variants`. (`set` is not ordered, unlike `dict`)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55428
Test Plan:
Run in CI
CC: ngimel wconstab ezyang bhosmer
Reviewed By: mruberry
Differential Revision: D27775284
Pulled By: robieta
fbshipit-source-id: c8c338fedbfb2860df207fe204212a0121ecb006
