Dynamically changing rive scene(for changing to different .riv file) in rive model component

Allow access to get and set "Rive Scene" and "Default state machine" property of model component in editor using go.get() and go.set() function for changing to different .riv file in runtime.

Similar like with sprite component we can get its "image" and "animation" propery using go.get() and set() to change sprite image to different resource at runtime.