This pull request vectorizes the 8-bit quantization vector-search path
in a similar was as the non-quantization path.
The assembly intrinsics are a bit more complicated than in the
non-quantization path, since we are operating on 8-bit integers and we
need to worry about preventing overflow. Thus, after loading the 8-bit
integers, they are extended into 16-bits before multiplying and
accumulating into 32-bit integers.
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Co-authored-by: debing.sun <debing.sun@redis.com>
