[torchao] finalize affine quant primitives

[metascroy]

🚀 The feature, motivation and pitch

torchao is planning on changing signatures of quant primitives. We need stability guarantees on these before we start onboarding backends to these new APIs.

Alternatives

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Additional context

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RFC (Optional)

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[metascroy]

"finalizing the quant primitives, I think it should be by the end of April" per @jerryzh168