[ENH] : Provide axis('equal') for Axes3D (replace PR #22705)

[patquem]

PR Summary

Closes #22570
Make axis('equal') available

@oscargus
Replace PR #22705 with a separate dedicated branch

PR Checklist

Tests and Styling

• Has pytest style unit tests (and pytest passes).
• Is Flake 8 compliant (install flake8-docstrings and run flake8 --docstring-convention=all).

Documentation

• New features are documented, with examples if plot related.
• New features have an entry in doc/users/next_whats_new/ (follow instructions in README.rst there).
• API changes documented in doc/api/next_api_changes/ (follow instructions in README.rst there).
• Documentation is sphinx and numpydoc compliant (the docs should build without error).

[scottshambaugh]

A 'what's new' entry would be great for this one (I'm pretty excited for all the 3.6.0 mplot3d features coming in)

[jklymak]

@patquem can you add a What New Note (doc/users/next-whats-new) and move back out of draft?

[scottshambaugh]

If @patquem is not reachable I'd say we merge without the what's new note and I can make a separate PR to add that in. Would hate to miss 3.6 on this great feature just because of that.

[QuLogic]

This needs a rebase to fix conflicts as well.

[jklymak]

@scottshambaugh maybe you could open a new PR based on this one, rebased and with the note? If you keep the authored-by comment in the commit message the original author will still get credit.

[patquem]

Hello everyone,
Sorry for not havin answered sooner.
Regarding the current PR I was faced to so many problems while I working on it that I didn't want (couldn't) spend more time on 'documentation'.
I see you are still working on the 3D aspect_equal to improve it .. and that's great !! :)
(next time, I will try to do things to the end)
Patrick

[scottshambaugh]

Thank you for your work on it!

[scottshambaugh]

This can close with the merge of #23409

[tacaswell]

Thank you for your work on this @patquem !