Add fast proxy benchmark

[poppinlp]

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

Hi. Thanks for the nice tool.

I recently use this in my work and I find out that there are some proxy plugins here. Seem's this one and fast-proxy are both under fastify org. So I'm interested in the benchmark result and add the benchmark here since this plugin looks more officially.

I haven't change the benchmark result in README since it depends on the running machine and you may update it. :)

[mcollina]

lgtm.

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Note that fast-proxy is a fork of this module without the fastify bits. We are trying to reconcile the two. Currently fast-proxy does not work with Fastify.