fix(cli): skip processes owned by other users and handle AccessDenied when stopping MAPDL

[germa89]

Description

• Add _can_access_process() and use it in stop() to skip processes not owned by the
  current user or that raise AccessDenied/NoSuchProcess when queried.
• Broaden exception handling in stop() to catch psutil.AccessDenied where appropriate.
• Make is_ansys_process() resilient to AccessDenied/NoSuchProcess and return False when
  process info cannot be accessed.
• Add unit test (test_pymapdl_stop_permission_handling) and adjust mocks to include
  username behavior to ensure permission edge-cases are handled without crashing.

Issue linked

Close #4256

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)

[Copilot]

Pull Request Overview

This PR fixes a critical bug where the pymapdl stop command would crash when encountering processes owned by other users or when access is denied to process information. The fix adds permission checking and proper exception handling to gracefully skip inaccessible processes.

Key changes:

• Added _can_access_process() helper function to verify process ownership before attempting operations
• Enhanced exception handling throughout to catch psutil.AccessDenied alongside psutil.NoSuchProcess
• Made is_ansys_process() resilient to permission errors by returning False when process info is inaccessible

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/ansys/mapdl/core/cli/stop.py	Added _can_access_process() function and improved exception handling to skip processes owned by other users
src/ansys/mapdl/core/launcher.py	Wrapped is_ansys_process() logic in try-except to handle AccessDenied and NoSuchProcess exceptions
tests/test_cli.py	Added comprehensive test for permission handling scenarios and updated mock processes to include username behavior

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[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.37%. Comparing base (566d59e) to head (a25aa7d).
⚠️ Report is 1 commits behind head on main.

❌ Your patch status has failed because the patch coverage (75.00%) is below the target coverage (90.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4281      +/-   ##
==========================================
+ Coverage   91.19%   91.37%   +0.18%     
==========================================
  Files         193      193              
  Lines       15726    15740      +14     
==========================================
+ Hits        14341    14383      +42     
+ Misses       1385     1357      -28     

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[germa89]

Skipping coverage as there aren't that many lines.

@pyansys-ci-bot LGTM.

[pyansys-ci-bot]

✅ Approving this PR because germa89 said so in here 😬