Allow more types of room sorting

Currently NeoChat only sorts by most recent activity first.

However other clients like Element allow sorting options like A-Z.

I personally always have it configured to sort by A-Z but show rooms with unread messages first. So it jumps a room to the top when it receives a new message, but once I read it goes back down to the A-Z ordering again.

Element allows this to differ per category so that would be nice to have.