Initial support for Hafas mode group configurations
This is far from complete: - Multiple matching configurations would need multiple queries it seems, we aren't doing that yet and just pick the first match. - The current format only covers access/egress modes, not direct modes, something JourneyRequest doesn't model properly yet. - Most Hafas endpoints don't have the necessary data yet. It's already good enough for basic combined bike/PT queries though, and helps to test the response parsing for those scenarios.