ci: adding docker compose files for testing

[germa89]

Description

As the title. The idea is to simplify the testing configuration.

Issue linked

NA

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 adds Docker Compose files for testing PyMAPDL against different MAPDL installations. The goal is to simplify testing configuration by providing containerized environments with various profile combinations for running tests locally or against remote MAPDL instances.

Key changes include:

• Addition of a comprehensive Docker Compose configuration with multiple profiles for different testing scenarios
• Creation of a flexible Dockerfile with multiple build targets for various testing configurations
• Addition of supporting scripts and configuration files for test execution

Reviewed Changes

Copilot reviewed 6 out of 9 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
docker/testing/docker-compose.yml	Comprehensive Docker Compose configuration with multiple profiles for testing PyMAPDL against different MAPDL setups
docker/testing/Dockerfile	Multi-stage Dockerfile with various build targets for different testing scenarios
docker/testing/start.sh	Bash script for running tests with environment variable handling and branch switching
docker/testing/mylocal.ip	Configuration file with localhost IP address for MAPDL
docker/MAPDL/make_container.rst	Updated file paths to reflect new directory structure
doc/source/getting_started/make_container.rst	Updated include path to point to reorganized documentation

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.31%. Comparing base (de1cf18) to head (d3f1fc6).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4186      +/-   ##
==========================================
- Coverage   91.31%   91.31%   -0.01%     
==========================================
  Files         193      193              
  Lines       15724    15731       +7     
==========================================
+ Hits        14358    14364       +6     
- Misses       1366     1367       +1     

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