Add support for MXFP8 All gather

[avizon-aws]

Currently when trying to use TP All gather with MXFP8, it gives an unimplemented error for the all gather operation. This PR adds support for MXFP8 all gather which will enable better performance as it will reduce the bandwidth required for the gather compute.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/ao/3435

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❌ 1 New Failure, 7 Pending

As of commit f96d168 with merge base 0975a40 ():

NEW FAILURE - The following job has failed:

• Code Analysis with Ruff / build (3.9) (gh)
  Process completed with exit code 1.

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[danielvegamyhre]

cc @vkuzo @drisspg

[vkuzo]

looks reasonable, would you mind rebasing as we've landed some refactors to MXTensor recently?

just curious, which framework are you using TP + mxfp8 from?

[avizon-aws]

I think I already rebased just before creating the PR (yesterday night), so it should be up to date with mainline. I fixed the ruff formating to pass the workflows, I think one of the workflow was failing due to a missing tag on the PR, i think the right tag should be "add new feature", i wasnt able to add it, I think i dont have the permission for it.

I tried the TP AG using native pytorch, i created a test script for it, didnt use any other framework currently. I updated the sharding strategy for to_mx due to which it required the TP AG.

[danielvegamyhre]

lgtm! will leave approval for @vkuzo who i think is also taking a look at this.

@avizon-aws to fix the code analysis ci job, please run the linter with ruff check --fix torchao/ test/ and ruff format torchao/ test/