Refactor renderer.py

[chillenzer]

During the work on #4817, some peculiarities of lib/python/picongpu/pypicongpu/rendering/renderer.py (and potentially other such files) popped up like the seemingly overly restrictive type guarding going against the idea of inheritance and duck typing. @BrianMarre and I agreed that it might be a good idea to refactor that into a more robust version. I think this should reasonably put onto the agenda when that file is touched the next time, so this issue is not immediately actionable, but if someone has time to go ahead with it...