autoquant support for fp8

[msaroufim]

Recently came across this repo that's doing fp8 inference https://github.com/aredden/flux-fp8-api/blob/main/float8_quantize.py

It's getting popular enough that we should consider just making this a setting for autoquant

[jerryzh168]

cc @jainapurva @drisspg @HDCharles

[jainapurva]

PRs: #866 #1175 #946