node websockets proxy with session

ws.js

@dougwilson thanks for the quick response. Yeah, I've read most of the session lib source and couldn't see a reason for it not work.

I found a way, by manually calling session on the express websockets upgrade request handler:

```js
import Express from 'express'
import ExpressSession from 'express-session'
import proxy from 'http-proxy-middleware'

const session = ExpressSession({ ... })

const websocketsProxy = proxy('/websockets', {
  target: CONFIG.backendServerURL,
  changeOrigin: true,
  ws: true,
  onProxyReqWs: (proxyReq, req, socket) => {
    proxyReq.setHeader('Authorization', `Bearer ${req.session.accessToken}`)
  },
})

const app = Express()
app.use(session) // Handles creating/reading session in normal HTTP requests

const server app.listen(PORT)

server.on('upgrade', (req, socket) => {
  // The only thing I dislike is passing the empty `{}` object as a fake `response`
  // object, which the session object shouldn't need here
  session(req, {}, () => {
    // Calls proxy when req.session is already present
    websocketsProxy.upgrade(req, socket)
  })
})
```

Can you think of way of doing this that looks less hacky?

Thanks!