[Kernel] AQ AZP 3/4: Asymmetric quantization kernels

[ProExpertProg]

This PR adds kernels for asymmetric quantization of activations. Tests are included.

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[github-actions]

👋 Hi! Thank you for contributing to the vLLM project.
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🚀

[ProExpertProg]

/ready

[varun-sundar-rabindranath]

LGTM! left a few nit comments.

[tlrmchlsmth]

I spotted a potential issue in the ROCM saturating cast from int32 -> fp32 codepath

[tlrmchlsmth]

I left one minor comment that it would be good to explain the rounding mode scenario in a bit more detail for future readers, but otherwise looks good

[tlrmchlsmth]

Thanks for adding the test

[mgoin]

LGTM