Support setup.py and more ScanCode PyPI package manifests

[pombredanne]

We should support additional dependency resolution inputs beyond requirements.
ScanCode supports most if not all Python package metadata formats. We should add support for these.

One design could be to include the parsing from SCTK directly here like we did for requirements. Alternative designs could be to accept an SCTK scan as an input or a list of Package URLs + vers or a list of "dependencies" as reported by SCTK .

• Support setup.py/setup.cfg as an input for dependency resolution
• Support Pipfile/lock as an input for dependency resolution
• Support pyproject.toml (including poetry) as an input for dependency resolution
• Support wheels and sdists as an input for dependency resolution