Add support for pylock.toml (fixes #4638)

[royalvedant]

fixes #4638
This PR adds initial support for pylock.toml in scancode-toolkit.

Changes:

• Detect pylock.toml files during scanning
• Parse pylock.toml format
• Extract Python package dependencies
• Integrate parsing into the scancode package pipeline

This enables scancode to recognize pylock.toml as a valid Python lockfile format and include it in dependency analysis and SBOM generation.