Simplify use of ISA specific routines through a unified API for static methods

[r-devulap]

Simplifies use avx512/avx2 specific methods via a single header file which when complied with the right AVX-512/AVX2 flags it calls the corresponding sort routines. Example:

#include "x86simdsort-static-incl.h"
int main()
{
    const int size = 1000;
    double arrd[size];
    x86simdsortStatic::qsort(arrd, size);
    return 0;
}

When compiled with -mavx512vl -mavx512dq, it calls the avx512_qsort routine and when compiled with -mavx2 it calls the avx2_qsort.

Todo:

• Update README

[sterrettm2]

Looks good! I just had a few comments I would like you to consider before merging it

[sterrettm2]

Looks good to me!