Add coverage guided fuzzing into to Deno's tool kit.

[jereklas]

I really appreciate all the effort that has been put into having all tooling natively supported by Deno. The only thing that I feel is missing at this point is a built-in coverage guided fuzzing solution. Golang for example included one in their standard library a couple years ago as part of their 1.18.0 release and is something my company uses heavily. I would like to be able to write server code with Deno, and the last sticking point I have at this point is "how do I fuzz test?", so hopefully others also find this a worthwhile addition.