upstream revert to MUMPS 5.3 due to 5.4 bug for win32
Mumps 5.4 series doesn't work with Windows and Intel/MSVC compiler. As a result, emailed upstream devs and revert this "main" Git CMake branch to 5.3.5 MUMPS for now.
- added ability to switch MUMPS version to known versions in cmake/libraries.json via MUMPS_UPSTREAM_VERSION variable
- added examples to tests and simplified their scripting
- CMake: use modern practices with per-language add_compile_options generator expressions