feat: Add optional graphical target and rework graphics backend selection

[AlejandroFernandezLuces]

Description

Add a separate optional target from graphics installation, as required in ansys/pyansys#902

Checklist

• I have visited and read Develop PyMAPDL.
• I have tested my changes locally
• I have added necessary documentation or updated existing documentation.
• I have followed the PyMAPDL coding style guidelines.
• I have added appropriate unit tests that also ensure the minimal coverage criteria.
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved to the PR if any.
• I have assigned this PR to myself.
• I have marked this PR as draft if it is not ready to be reviewed yet.
• I have made sure that the title of my PR follows Commit naming conventions (e.g. feat: adding new MAPDL command)

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[codecov]

Codecov Report

Attention: Patch coverage is 89.09091% with 12 lines in your changes missing coverage. Please review.

Project coverage is 88.29%. Comparing base (e0dd5d6) to head (5f017d8).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3820      +/-   ##
==========================================
- Coverage   88.36%   88.29%   -0.08%     
==========================================
  Files         187      187              
  Lines       14761    14819      +58     
==========================================
+ Hits        13044    13084      +40     
- Misses       1717     1735      +18     

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[RobPasMue]

LGTM!

[AlejandroFernandezLuces]

Before going forward and modify the examples, do you agree with this approach for backend selection @germa89 @RobPasMue ? User facing API would change like this:

    >>> from ansys.mapdl.core import GraphicsBackend
    >>> mapdl.aplot(graphics_backend=GraphicsBackend.MATPLOTLIB)
    >>> mapdl.lplot(graphics_backend=GraphicsBackend.MATPLOTLIB)
    >>> mapdl.kplot(graphics_backend=GraphicsBackend.MATPLOTLIB)

[germa89]

@AlejandroFernandezLuces I did figure out what was the problem with the tests. There was a few:

1. One of the test was changing the default state of the MAPDL class to GraphicsBackend.MAPDL. That returns None when plotting (even if using return_plotter=True), hence the corresponding assertion errors. I did fix that test and add a check on the run_before_and_after function.

   eed1822 (Highly recommended to use patch!!
   ec45e05

2. In PyMAPDL we test that some docstrings include certain things, which the recent changes they wasnt. 568fb42

3. Also, wrong imports in here: 0963041

4. Additionally, the documentation requires for the methods to have docstrings... the decorator implemented was not respecting the docstring of the wrapped function. That be easily fixed with functools.wraps (very useful as well).
   2ad65a1

[germa89]

@AlejandroFernandezLuces are we missing anything here?

Btw, title must be changed since the scope has expanded .

[AlejandroFernandezLuces]

I was waiting for your feedback on the conversation about the decorator, from my side it is good to go as is. If you want to expand the current implementation of the decorator let me know.

Also, vulnerability check is failing, but it doesn't seem to be failing in anything I've modified..

[germa89]

I was waiting for your feedback on the conversation about the decorator, from my side it is good to go as is. If you want to expand the current implementation of the decorator let me know.

Also, vulnerability check is failing, but it doesn't seem to be failing in anything I've modified..

I just replied to the thread.

Do not bother about the vulnerability check. We will merge without it.

[germa89]

Overall, it looks good to me.

One last request will be to have a warning/exception if an user is using the old vtk argument. I am concerned that this argument might be passed around in the kwargs without having effect. Please do also add a test for this check.
Probably this is a good case for a decorator.

[germa89]

This PR is great! Thank you a lot @AlejandroFernandezLuces ! Great work!