Adapt CholmodSolver to (almost) arbitrary matrix types
This is follow-up change from the dune-istl Cholmod changes in https://gitlab.dune-project.org/core/dune-istl/-/merge_requests/424
Edited by Patrick Jaap
This is follow-up change from the dune-istl Cholmod changes in https://gitlab.dune-project.org/core/dune-istl/-/merge_requests/424