#2339 Expanded random() benchmarks, set structure for future benchmarks

[Jared-Sprague]

Moving the benchmarks grouped under major categories, like math/random*.bench.js to set the structure for future benchmarks to be created to keep it organized. And wanted to do this as part of someone else adding a new benchmark in #2339

[Zalastax]

I've fixed the error for the PR in https://github.com/Zalastax/p5.js/tree/fe-benchmarks. Let me know if you need any more help with making this PR mergeable again. Thanks for your time!

My fork is just a git pull upstream master --rebase and then git push origin fe-benchmarks -f.
If you want I can rebase the PR with what you see in that link.