Build room animations from rooms.json instead of already created stage

[evktalo]

Currently furniture animation data is read into Konva objects as custom fields, and the build into the room animations view from actual objects that have already been built into the Konva stage.

Instead, structure animation data in rooms.json so that it's not added to the furniture objects, but instead build later from the same rooms.json data separately.

I think it'll still be necessary to build/create the furniture as Konva objects (in stage?) before the animations can be created, as they refer to the actual furniture with node, but the aim is to not need to store the custom fields in the created furniture object.