Macos-pkg-builder

- Fix missing `FlatPackage` and `DistributionPackage` class declaration in `__all__` attribute
- Publish source distribution to PyPi and GitHub
- Remove deprecated `python3 setup.py test` from CI
- Strip Quarantine attributes from scripts and files during package creation

- Perform volume verification on whether Copy on Write (COW) is available
- Resolves crashing on HFS+ volumes.
- Add automatic detection of source file copying
- Resolves crashing when directories are passed to `pkg_script_resources`
- Set BSD 3-Clause License

- Resolve `open` error on component file generation

- Resolve packages embedding an empty pkg at `/`
- Regression from 2.0.0

- Implement new `FlatPackage` and `DistributionPackage` classes
- Intended for more advanced package configurations, including bundling multiple PKGs inside a single distribution package
- Implement more robust subprocess logging for errors
- Implement Copy on Write (COW) for package resources
- 20% faster package creation on average