hook up real nvfp4 grouped_gemm

[vkuzo]

Summary:

for nvfp4 + grouped_mm:

1. hooks up mslk's to_nvfp4 quantization kernel for token group
   activations
2. hooks up the nvfp4 recipe of torch._scaled_grouped_mm

still WIP

Test Plan:

pytest test/prototype/mx_formats/test_inference_workflow.py -s -k grouped_mm

[vkuzo]

Stack from ghstack (oldest at bottom):

• install debug expert token counters on nvfp4 moe test script #4322
• hook up hf + moe + nvfp4 script to lm_eval #4321
• wire up nvfp4 bmm #4320
• e2e example with HF model + MoE + torchao nvfp4 #4319
• -> hook up real nvfp4 grouped_gemm #4316

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/ao/4316

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❌ 1 New Failure, 8 Pending

As of commit b0697ac with merge base bfa7a94 ():

NEW FAILURE - The following job has failed:

• Run 1xH100 Tests / test (H100, linux.aws.h100, --pre torch torchvision torchaudio mslk --index-url https://download.... / linux-job (gh)
  RuntimeError: Command docker exec -t caf86d25375f6328914df9f0e445df05470f85667f22a1d2af7c42a320db1c3d /exec failed with exit code 1

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[vkuzo]

this isn't used so deleting