[X86][Costmodel] Load/store i16 Stride=6 VF=16 interleaving costs

The only sched models that for cpu's that support avx2
but not avx512 are: haswell, broadwell, skylake, zen1-3

For this tuple, measuring becomes problematic since there's a lot of spilling going on,
but apparently all these memory ops do not affect worst-case estimate at all here.

For load we have:
https://godbolt.org/z/5qGb9odP6 - for intels `Block RThroughput: <=106.0`; for ryzens, `Block RThroughput: <=34.8`
So pick cost of `106`.

For store we have:
https://godbolt.org/z/KrWcv4Ph7 - for intels `Block RThroughput: =58.0`; for ryzens, `Block RThroughput: <=20.5`
So pick cost of `58`.

I'm directly using the shuffling asm the llc produced,
without any manual fixups that may be needed
to ensure sequential execution.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D110593