Initial checklist

• I understand this is a bug report and questions should be posted in the Community Forum
• I searched issues and couldn’t find anything (or linked relevant results below)

Link to runnable example

No response

Steps to reproduce

Currently there is no way to add authentication to this websocket connection https://github.com/transloadit/uppy/blob/main/packages/%40uppy/companion/src/server/socket.js#L20

Expected behavior

Allow to inject a auth callback in the configuration to verify who is connecting.

I'm happy to contribute a fix in case this is a valid concern from your perspective.

Actual behavior

No authentication possible.