Store PyPIConGPU species instance in the PICMI species instance #5445
Description
We should store the PyPIConGPU species instance in the PICMI species after the translation by get_as_pypicongpu().
In the translation of the PICMI species instances to PyPIConGPU species instances, we currently store the mapping between PICMI and PyPIConGPU species instances in a dict which we pass back to the PICMI simulation instance which then passes it to everything else that is species related, see here.
This strong coupling makes implementing anything new species related more difficult than necessary since one needs to know how to get that mapping dict. If we store the PyPIConGPU species in the PICMI species we can change this to a weak coupling and make implementation of some species related stuff easier.