"clean" will delete all node_modules and dist folders, and the fuzzer
C++ build directories. Deleting all files mentioned in .gitignore files
would work even better, but there does not seem to be a still maintained
project for that.

Options are handled in a consistent way across CLI and Jest
integration, so that both use the same names with the same semantics.

Yargs automatically converts numeric CLI arguments to numbers. As the
fuzzer argument handling only expects strings, enforce the argument
types.

The additional complexity does not add any value to the test and only
prolongs the CI pipeline.

The test adds unnecessary long runtime to the CI pipeline. A more
relaxed one tests the feature good enough.