faster vqsort when <4 keys per vector: add new Sort16Rows cases to BaseCase

[a-eridani]

I added sorting networks for cases, when <4 keys fits the register. BaseCase::funcs:

1. <= 16: if 1 key, use Sort16Rows<1>
2. <= 32: if 2 keys, use Sort16Rows<2>

Also, kLPK in BaseCaseNumLanes is no longer needed, because cases for <4 added. I removed it.

bench_sort: for n <= 128 a single bench is terrible noisy, so now 30 sorts of 30 different buffers are measured for them in one measurement.

Final speedup(I alternated many benches and took the median, apple m5)

type	n	speedup
U128	16	+326.3%
k+v=128	16	+270.9%
i64	32	+355.8%
U128	32	+58.6%
k+v=128	32	+56.5%
i64	64	+71.7%
U128	64	+53.0%
k+v=128	64	+47.1%
i64	128	+59.2%
U128	128	+43.8%
k+v=128	128	+39.9%
i64	10000	+26.8%
U128	10000	+23.6%
k+v=128	10000	+22.6%

for n=1e4 i used uniform32.
Other types remain unchanged