Allow custom overrites for package resolving and optional sys.path support

[spezifant]

Motivation

Certain build systems or configurations have Python packages located in a non-default path. Those are not found by Codegen per default.

Content

Codegen now considers the PYTHONPATH environment variable when resolving packages.

Testing

Added unit tests which resolve packages only when the PYTHONPATH is set in a correct way.

Please check the following before marking your PR as ready for review

• I have added tests for my changes
• I have updated the documentation or added new documentation as needed

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3 out of 4 committers have signed the CLA.

✅ spezifant
✅ christinewangcw
✅ tomcodgen
❌ Matthias Bartelt

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[eacodegen]

Would it be possible for you to add two options:

1. Make respecting sys.path opt in
2. Add additional overrides

Example: if codegen is installed a virtual environment, we wouldn't want to make the user set PYTHONPATH/install it into the project environment. We'd also not want to accidentally include code from their virtual enviornment

[eacodegen]

Thanks for the PR by the way! Let us know if you ever have any questions.

[tkfoss]

thank you @spezifant

[github-actions]

🎉 This PR is included in version 0.37.0 🎉

The release is available on GitHub release

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