Run unixbench via dev_bench

[CvvT]

Fwiw, since we already have dev_bench it would be nice if the benchmarks could be made a part of that. I've already put in effort when building it to aim towards something we can use longer-term to keep track of and manage regressions and so on.

No worries if integrating into that framework is too difficult rn though (since as I understand it, unixbench is "fixed time, measure work units" type benchmark, while the framework I've built is a "fixed work units, measure time"), but just making a note here that we should probably have a single way to run all our benchmarks.

Basically, if we merge some version of this without integrating with dev_bench, it would be helpful to open up an issue to track this work. Please feel free to assign me to it and I'll (eventually) get to it.

Originally posted by @jaybosamiya-ms in #711 (comment)