Provide Room in the content block callback for RoomScope

[bcherry]

This makes RoomScope more closely match other helpers by providing two ways to get the room - either through @EnvironmentObject or through a param.

It simplifies the use of multiple delegates on Room, such as with Krisp filtering, by allowing you to add them after room creation without adding extra custom views:

  RoomScope(url: ... 
                      token: ...,
                      connect: true,
                      enableCamera: true,
                      enableMicrophone: true) { room in
    room.add(delegate: krispProcessor)
    return VStack {
        ForEachParticipant { _ in
            VStack {
                ForEachTrack(filter: .video) { _ in
                    MyVideoView()
                }
            }
        }
    }
}

[bcherry]

@hiroshihorie digging in a little more i found it's cleaner to just pass a room (for Krisp), but I do think that RoomScope is a bit messy because all of its parameters aren't really stateful. If it's going to expose token, enableMicrophone, etc it needs to respond to changes to them but right now those are just initialization params only. We should consider reworking them as bindings - so enableMicrophone is directly connected through and toggling it on or off toggles mute, and token is listening so you can have it set to nil initially while it gets fetched, and the room will automatically connect when a value is set.