Knock client does not allow changing of user

[isaachinman]

We noticed some 403 logs in our application.

Long story short, this is a reproducible error that occurs because the Knock client, as a global singleton, is not correctly handling changing of user.

The teardown function is more or less useless.

If you first initialise a client with user-1, and then reauthenticate with user-2, the client will still attempt to fetch user-1, and will get a 403.

I assume this issue has not yet been reported because most of your customers use React context/hooks, or something.

For now we will work around this issue by putting the Knock client inside a zustand store itself, instead of treating it as a global singleton.

I would suggest two action steps:

1. Expose a proper teardown function that actually does what it says, instead of only disconnecting a websocket
2. Correctly handle subsequent .authenticate calls. The UserClient should ideally just be entirely recreated