[disc][porousmediumflow][co2] Use discretization tag instead of enum as template argument.

5 jobs for !2844 with feature/discretization-tags-introduction
detached
Status Name Job ID Coverage
  Trigger
passed full-dune-latest-release-clang

passed full-dune-latest-release-gcc

passed full-dune-master-gcc

passed minimal-dune-latest-release-gcc

 
  Downstream Modules
passed trigger lecture