Auto add slack rooms / direct messages to community grouping

[seanfarley]

Hi there, thanks for making this bridge! I was just wondering if it'd be possible to auto-create a community group with a particular slack instance. It seems both mautrix-facebook and mautrix-hangout have this option (e.g. https://github.com/spantaleev/matrix-docker-ansible-deploy/blob/master/docs/configuring-playbook-bridge-mautrix-facebook.md#set-up-community-grouping). I would love to see this feature if you think it's possible (currently, I manually add the rooms and users but this suffers from new chats having to be added by hand each time). I can try to help code, if that makes sense, too!

[dreamflasher]

Would love to see that too!