todo: merge AVX-512 version of PQFastScan

[alexanderguzhva]

Faiss PR facebookresearch/faiss#3276

AVX-512 implementation for PQFastScan for QBS.
For local benchmarks on 4th gen Xeon, the QPS is up to 10% higher, mostly for a single query case. But as far as I remember, production cases would show higher performance improvements.

It cannot be cherry-picked or copy-pasted, because Faiss baseline uses #ifdef mechanism for deciding whether to use AVX-512, and Knowhere uses dynamic hooks. Some additional code is needed.

[github-actions]

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[alexanderguzhva]

/reopen

[sre-ci-robot]

@alexanderguzhva: Reopened this issue.

In response to this:

/reopen

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