Allow re-auth

[lwansbrough]

Hey there, I've got a suggestion for auth: It would be helpful to be able to re-auth at any point, in the case where the user's session is going to expire while the user is connected.

[ghost]

Yeah definitely! Thanks for the suggestion. There's a couple ways to do this, I don't have an opinion around the implementation at the moment.

My initial thought is:

1. NaiaServer could expose a method like: send_reauth_request(key: UserKey, timeout: Duration)
2. Which triggers a ReauthRequest event on NaiaClient, which must be responded to using a send_reauth_response(reauthEvent: Event).
3. Then in NaiaServer you could either reuse the "on_auth()" callback method, or have a new "on_reauth()" callback, that processes the reauth event payload.
4. If a user does not successfully re-auth within the given timeout, then they are forcibly disconnected.

Anyone else have thoughts on how to go about this? Any good examples of other crates that have a pattern for this?