currently, it looks the value for ZMF is based on XMF and YMF.
ideally, the ZMF is part of the primary varialbes, it does not need to
be calculated based on XMF and YMF.
there is some refactoring that we can do here.
so the FlowProblemComp can output ecl style output.
it duplicates the OutputBlackoilModule and GenericOutputBlackoilModule
for compositional related output for now.