Remove "reflection" when changing JSON parameters from Topography elements

Problem:

The Stairs class (and possibly others?) includes logic in the constructor (drawing the treads). The constructor is not called again when the attribute parameters are changed in the JSON but instead force-set by reflection.

The strategy is now to remove the reflection and replace it with a new abstract method setAttributes(attributes) in class ScenarioElement. This means the call to setAttributes of ReflectionAttributeModifier should be replaced by a setAttributes of the element in https://gitlab.lrz.de/vadere/vadere/blob/develop/VadereGui/src/org/vadere/gui/components/view/ScenarioElementView.java#L146 ).

This will be implemented in the separate branch remove_reflection.