[apps/qsort] implement quicksort benchmark used by kprotty
Benchmark results:
Measured on my AMD Ryzen 7 4800H laptop with 8 cores 16 hwthreads and 16GiB RAM
go tokio rayon emper
1. 384ms 527ms 193ms 218ms
2. 370ms 526ms 202ms 226ms
3. 412ms 529ms 187ms 251ms
4. 378ms 525ms 149ms 222ms
5. 396ms 531ms 144ms 251ms
avg: 388ms 527ms 175ms 233ms