Usage:

```js
interface SocketData {
  name: string;
  age: number;
}

const io = new Server<ClientToServerEvents, ServerToClientEvents, InterServerEvents, SocketData>();

io.on("connection", (socket) => {
  socket.data.name = "john";
  socket.data.age = 42;
});
```

Usage:

```js
const { App } = require("uWebSockets.js");
const { Server } = require("socket.io");

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

server.attachApp(app);

app.listen(3000);
```

The Adapter prototype is updated so we can benefit from the publish
functionality of uWebSockets.js, so this will apply to all adapters
extending the default adapter.

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

Related:

- #3601
- socketio/engine.io#578

The Socket instance is only considered connected when the "connection"
event is emitted, and not during the middleware(s) execution.

```js
io.use((socket, next) => {
  console.log(socket.connected); // prints "false"
  next();
});

io.on("connection", (socket) => {
  console.log(socket.connected); // prints "true"
});
```

Related: #4129

See also: socketio/socket.io-adapter@88eee59

`srv.close()` only closes the underlying HTTP server, but this does not
terminate the existing WebSocket connections.

Reference: https://nodejs.org/api/http.html#serverclosecallback

Usage:

```js
socket.timeout(5000).emit("my-event", (err) => {
  if (err) {
    // the client did not acknowledge the event in the given delay
  }
});
```

The ack was not properly removed upon timeout, and could be called
twice.

Related: f0ed42f

Diff: 4.3.2...4.4.0