feat: add an implementation based on uWebSockets.js

```js
const { App } = require("uWebSockets.js");
const { uServer } = require("engine.io");

const app = new App();
const server = new uServer();

server.attach(app);

app.listen(3000);
```

Reference: https://github.com/uNetworking/uWebSockets.js

Related: https://github.com/socketio/engine.io/issues/578