Initial phase presence for cell-centered models gets evaluated always with first grid vertex

Suggestion: the signature of inititalPhasePresence should be different for box and cc discretizations. Like dirichlet. See e.g. https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/blob/master/dumux/porousmediumflow/3pwateroil/model.hh line 183 for an example.