[RFC] New S3 Benchmark

Hi Guys, Earlier this week I was working on investigating the impact of OMAP performance on RGW and wanted to see if putting rocksdb on ramdisk would help speed up bucket index updates. While running tests I found out that the benchmark tool I was using consumed roughly 15 cores of CPU to push 4K puts/second to RGW from 128 threads. That wasn't really viable, so I started looking for alternate S3 benchmarking tools. COSBench is sort of the most well known choice out there, but it's a bit cumbersome if you just want to run some quick tests from the command-line. I managed to find a simple yet very nice benchmark written in go developed by Wasabi Inc called s3-benchmark. While it works well, it really only targets single buckets and is designed more for AWS testing than for Ceph. I forked the project and pretty much refactored the whole thing to be more useful for the kind of testing I want to do. It's now at the point where I think it might be ready to experiment with. S3 benchmarking has been a semi-recurring topic on the list so I figured other folks might be interested in trying it too and hopefully providing feedback. The new benchmark is called hsbench and it's available here: https://github.com/markhpc/hsbench See the README.md for some of the advantages over the original s3-benchmark program it was forked from. I consider this release to be alpha level quality and disclaim all responsibility if it breaks and deletes every object in all of your buckets. Consider yourself warned. :) Mark