chore: add tutorial for python gen-build-spec and support more build tools

[behnazh-w]

Summary

This PR adjusts the gen-build-spec tutorial for the Python and extends support for additional Python build tools, and refactors registries to make them build tool agnostic.

Description of changes

• Adds a comprehensive tutorial for using the Python gen-build-spec command, providing step-by-step instructions, usage examples, and best practices to help users get started effectively.
• Extends the functionality of gen-build-spec to support a wider range of build tools (e.g., setuptools, poetry, flit), increasing versatility across Python project types.
• Refactors registry handling logic to decouple it from specific build tools. Registries are now organized based on the PURL (Package URL) namespace, enabling a more flexible, scalable, and tool-agnostic approach
• Updates related documentation to reflect these changes and ensure consistency.