Resolve "DORiE installation on Mac (homebrew does not support --with-mpi any more)"

What does this MR do?

• Make CMake configuration to only work with targets (apart from DUNE_LIBS).
  • Automatically link to dependencies when registering tests.
  • Remove unused find_package calls.
• Update installation instructions for macOS, which now require building HDF5 from source (see #149 (closed)).

Is there something that needs to be double checked?

• @hbauser, does local installation work on your machine?

Can this MR be accepted?

• Implemented stuff
• Pipeline passing
• [ ] Added entry to CHANGELOG.md

Related issues

Closes #149 (closed)