refactor(parser): strategy pattern for documentation parsing

[lars-reimann]

Summary of Changes

• Use strategy pattern and dependency injection to eventually support different documentation format.
• Add tests for NumpyDoc parser
• Generally clean up structure of the package-parser

[github-actions]

MegaLinter status: ✅ SUCCESS

Descriptor	Linter	Files	Fixed	Errors	Elapsed time
✅ CREDENTIALS	secretlint	yes		no	4.22s
✅ GIT	git_diff	yes		no	0.01s
✅ PYTHON	bandit	40		0	1.08s
✅ PYTHON	black	40	0	0	1.45s
✅ PYTHON	flake8	40		0	1.19s
✅ PYTHON	isort	40	0	0	0.23s
✅ PYTHON	mypy	40		0	44.4s
✅ PYTHON	pylint	40		0	10.19s

See errors details in artifact MegaLinter reports on CI Job page
Set VALIDATE_ALL_CODEBASE: true in mega-linter.yml to validate all sources, not only the diff

[github-actions]

🎉 This PR is included in version 1.31.0 🎉

The release is available on GitHub release

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