If a client that does not support bouncer-networks connects to soju, it will see the chat history only from the point it connected to the bouncer, as opposed to since when the bouncer connected to the network.

It is expected that all clients that connect to the bouncer see the same chat history, regardless of their support for bouncer networks.

Previous patch/discussion: https://lists.sr.ht/~emersion/soju-dev/%3C20211211085225.16431-1-ecs%40d2evs.net%3E