Refactor StreamFirstUserJoin to onMessage and add new chat alerts to /dashboard/events/custom

[Satont]

Currently we watching user join even via irc, but we should use message instead https://github.com/twirapp/twir/blob/main/apps/bots/internal/chat_client/handlers_user_join.go#L76C33-L76C52

And we need to add new event to chat alerts section, with changes on backend.

[Satont]

In events on frontend this even should be called User joined first per stream, he already presented in events, we need just to rename.

[Satont]

We should use tempoiral/asynq for such task, because we do not care about result of execution.