Use numpy testing utilities instead of custom close_to*

[erik-werner]

Closes #6748

What is this PR about?
This PR replaces our custom close_to* functions with numpy testing asserts with nice error displays and more careful array shape checking.

Checklist

• Explain important implementation details 👆
• Make sure that the pre-commit linting/style checks pass.
• Link relevant issues (preferably in nice commit messages)
• Are the changes covered by tests and docstrings?
• Fill out the short summary sections 👇

Major / Breaking Changes

• ...

New features

• ...

Bugfixes

• Fix test_simplex_accuracy() which was previously broken

Documentation

• ...

Maintenance

• Replace custom close_to functions with numpy equivalents

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📚 Documentation preview 📚: https://pymc--6961.org.readthedocs.build/en/6961/

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[codecov]

Codecov Report

Merging #6961 (11c953c) into main (03f9f72) will decrease coverage by 20.20%.
The diff coverage is n/a.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #6961       +/-   ##
===========================================
- Coverage   89.01%   68.82%   -20.20%     
===========================================
  Files         100      100               
  Lines       16859    16857        -2     
===========================================
- Hits        15007    11601     -3406     
- Misses       1852     5256     +3404     

see 63 files with indirect coverage changes

[erik-werner]

@ricardoV94 Any idea about what happened here? The measured code coverage has gone down by 20%.

[ricardoV94]

The codecov is stupid, it doesn't rerun after the first time, and if that failed that's what stays: #6660

No need to worry about it in your case

[welcome]

Congrats on merging your first pull request! 🎉 We here at PyMC are proud of you! 💖 Thank you so much for your contribution 🎁

[ricardoV94]

Thanks a ton @erik-werner