Feat: Channel Groups

[WalrusSoup]

I think that auto-managed channel groups should be added to this SDK.

When an inbound message is received, wrapping the callback with a function to move that channel out of the channel group and subscribe to it would be nice. As of right now, if we want to start having lots of connections we need to frankenstein things together and manage it outside the chat-sdk.

I think this is within scope of the project.

[piotr-suwala]

Hey, @WalrusSoup!

I'll get back to you with this.