Introduce new room ID resolver

With GraphQL, having a resolver which fetches the whole room makes less sense. The components should decide, which properties they need, and use their own specialized queries. A resolver still makes sense to retrieve the roomId for a shortId.

Furthermore, the resolver previously converted the roomId UUID to use the legacy format without dashes. Components using GraphQL then had to convert it back.

Changing this behavior across the whole application would require a lot of refactoring. Therefore, the old resolver is kept and has been renamed to legacyRoomResolver. It can be removed once the whole application uses the GraphQL API. Therefore, a new roomIdResolver has been added. This resolver only returns the roomId and should be used for new code which uses the GraphQL API.

The legacyRoomResolver and Room are now deprecated.