feat: node/element selection commands returning selected ids

[moe-ad]

Description

Currently, commands such as mapdl.nsel() or mapdl.esel() will return a numpy array of selected objects' IDs. This is extremely useful when scripting since the selected IDs can be saved in a variable to be accessed later. Similar commands like mapdl.esln() or mapdl.nsle() do not have this behavior. Instead they return some selection status string from the running mapdl instance.

This PR adds the described functionality to the mapdl.esln() and mapdl.nsle() commands.

Issue linked

This PR will close #3635

Checklist

• I have visited and read Develop PyMAPDL.
• I have tested my changes locally
• I have followed the PyMAPDL coding style guidelines.
• 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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[moe-ad]

Before:

After:

Looks like that is everything that requires changing. Pinging @germa89 incase there is anything else to take note of.
@clatapie thanks for our discussions on this.

[germa89]

thank you a lot for this @moe-ad :). However, for this to be approved, you need to add some unit tests. I'm sure you know the procedure, but in case you have any doubt please check: https://mapdl.docs.pyansys.com/version/stable/getting_started/develop_pymapdl.html#unit-testing

Which you can reach from main documentation page https://mapdl.docs.pyansys.com :

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.06%. Comparing base (e83f46c) to head (0a824bb).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3636      +/-   ##
==========================================
- Coverage   87.08%   87.06%   -0.02%     
==========================================
  Files         187      187              
  Lines       14679    14683       +4     
==========================================
+ Hits        12783    12784       +1     
- Misses       1896     1899       +3     

[moe-ad]

@germa89 , thanks for the guide. I have added the tests.

[germa89]

LGTM! Thank you a lot @moe-ad ! Feel free to merge!

[jorgepiloto]

Congrats on this, @moe-ad 🚀