REFACTOR: Enforce design check in extensions

[SMoraisAnsys]

Description

Enforce design checking in extensions and refactor the tests to avoid useless mock, and define common fixtures.

Issue linked

Related to #5516

Checklist

• I have tested my changes locally.
• I have added necessary documentation or updated existing documentation.
• I have followed the coding style guidelines of this project.
• I have added appropriate tests (unit, integration, system).
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved by the PR if any.
• I have agreed with the Contributor License Agreement (CLA).

[ansys-reviewer-bot]

Thanks for opening a Pull Request. If you want to perform a review write a comment saying:

@ansys-reviewer-bot review

[codecov]

Codecov Report

Attention: Patch coverage is 95.45455% with 2 lines in your changes missing coverage. Please review.

Project coverage is 85.12%. Comparing base (ae51af8) to head (2440990).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6433      +/-   ##
==========================================
- Coverage   85.13%   85.12%   -0.01%     
==========================================
  Files         176      176              
  Lines       66944    66963      +19     
==========================================
+ Hits        56990    57004      +14     
- Misses       9954     9959       +5     

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Samuelopez-ansys]

Great!

[SMoraisAnsys]

Great!

Thanks for fixing the unit tests