feat: [FC-0074] add static type checking for documentation purposes

[mariajgrimaldi]

Description

This PR supports mypy based on what's already implemented for the filter tooling. The aim is to gradually start refactoring the library so it's more type-aware by starting to type what's currently here without any modifications to the codebase, mainly changing method signatures.

⚠️ Properly supporting mypy in this repo might need more adjustments and reactors so all types make sense, but this is a starting point for developers to start using type hints and understanding what their filters signatures return.

Testing instructions

You can run tox -e quality or review the workflow run here: https://github.com/openedx/openedx-filters/actions/runs/13133404193/job/36643330405?pr=250#step:6:29

Deadline

"None" if there's no rush, or provide a specific date or event (and reason) if there is one.

Checklists

Check off if complete or not applicable:

Merge Checklist:

• All reviewers approved
• Reviewer tested the code following the testing instructions
• CI build is green
• Version bumped
• Changelog record added with short description of the change and current date
• Documentation updated (not only docstrings)
• Code dependencies reviewed
• Fixup commits are squashed away
• Unit tests added/updated
• Noted any: Concerns, dependencies, migration issues, deadlines, tickets

Post Merge:

• Create a tag
• Create a release on GitHub
• Check new version is pushed to PyPI after tag-triggered build is
  finished.
• Delete working branch (if not needed anymore)
• Upgrade the package in the Open edX platform requirements (if applicable)

[openedx-webhooks]

Thanks for the pull request, @mariajgrimaldi!

This repository is currently maintained by @openedx/hooks-extension-framework.

Once you've gone through the following steps feel free to tag them in a comment and let them know that your changes are ready for engineering review.

🔘 Get product approval

If you haven't already, check this list to see if your contribution needs to go through the product review process.

• If it does, you'll need to submit a product proposal for your contribution, and have it reviewed by the Product Working Group.
  • This process (including the steps you'll need to take) is documented here.
• If it doesn't, simply proceed with the next step.

🔘 Provide context

To help your reviewers and other members of the community understand the purpose and larger context of your changes, feel free to add as much of the following information to the PR description as you can:

• Dependencies

  This PR must be merged before / after / at the same time as ...

• Blockers

  This PR is waiting for OEP-1234 to be accepted.

• Timeline information

  This PR must be merged by XX date because ...

• Partner information

  This is for a course on edx.org.

• Supporting documentation
• Relevant Open edX discussion forum threads

🔘 Get a green build

If one or more checks are failing, continue working on your changes until this is no longer the case and your build turns green.

---

Where can I find more information?

If you'd like to get more details on all aspects of the review process for open source pull requests (OSPRs), check out the following resources:

• Overview of Review Process for Community Contributions
• Pull Request Status Guide
• Making changes to your pull request

When can I expect my changes to be merged?

Our goal is to get community contributions seen and reviewed as efficiently as possible.

However, the amount of time that it takes to review and merge a PR can vary significantly based on factors such as:

• The size and impact of the changes that it introduces
• The need for product review
• Maintenance status of the parent repository

💡 As a result it may take up to several weeks or months to complete a review and merge your PR.

[sarina]

I'm not super familiar with using mypy for typing but this looks good and well-documented to me.