repo_management/argparse.py:
Add `ArgParseFactory`, which serves as an argparse.ArgumentParser
factory (new variants are implemented as classmethods).
The class provides a generic constructor, that offers a default parser
with a verbose argument and a description, alongside a specific one for
the db2json script.
Additionally, helper methods are provided to transform strings to Path
instances, while ensuring that they are either an existing file or
directory.

tests/test_argparse.py:
Add tests for all of `ArgParseFactory`.