[!300] Allow grid analysis with custom analyzing executable

Merge branch 'feature/enhanced-analyze-grid' into 'master'

ref:extensions/dune-codegen @rhess You might want to have a look. I changed
the naming scheme of the csv file as well to make sure it is always written to
the build directory.

See merge request [extensions/dune-codegen!300]

  [extensions/dune-codegen!300]: gitlab.dune-project.org/extensions/dune-codegen/merge_requests/300