Adds uWebSockets server

[streamich]

This PR adds uWebSockets server.

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

[jsumners]

Why is it fair to compare an HTTP framework with a Web Sockets framework?

[streamich]

@jsumners I guess you imply that uWebSockets library is a "Web Sockets framework". uWebSockets is a library which provides an HTTP server as well as a WebSocket server. The benchmark in this PR only tests the HTTP server part; I assume the WebSocket implementation of uWebSocket would be even faster. But that indeed would not be fair.

[Eomm]

It is a C++ server if I'm not wrong, so the comparison is tricky for the reader

[streamich]

@Eomm nope, it is JavaScript, you can see the route handler in this PR: https://github.com/fastify/benchmarks/blob/162467d8c8b8d28d22d97d6113bf23f672f8910f/benchmarks/uWebSockets.js

[Eomm]

The app var is not 😅

[streamich]

Essentially these benchmarks now are deceiving the reader, uws is about 2x faster than fastify, but the whole purpose of this repo is to promote fastify.