REFACTOR: Add examples folder and rework download logic

[SMoraisAnsys]

Description

This PR consists in refactoring the downloads logic. While doing so, an architecture refactoring was performed and a folder examples is now under ansys.aedt.core. It contains the modified dowloads.py module and can be extended with other actions related to the examples.

The download refactoring consist in:

• simplifying how the download calls are performed: use input github_relative_path to provide the path to the file/folder in github, use input filter_func to specify files/folders to be filtered, use strip_prefix to remove the original structure (e.g. allowing to download the file "pyaedt/edb/Galileo.aedb/GRM32ER72A225KA35_25C_0V.sp" without creating locally "pyaedt/edb/Galileo.aedb");
• safely constructing a URL using the user-provided input.

Issue linked

Associated to #5504

Checklist

• I have tested my changes locally.
• I have added necessary documentation or updated existing documentation.
• I have followed the coding style guidelines of this project.
• I have added appropriate tests (unit, integration, system).
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved by the PR if any.
• I have agreed with the Contributor License Agreement (CLA).

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[codecov]

Codecov Report

Attention: Patch coverage is 85.11628% with 32 lines in your changes missing coverage. Please review.

Project coverage is 85.13%. Comparing base (a3ecaf0) to head (f67683d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6055      +/-   ##
==========================================
- Coverage   85.14%   85.13%   -0.01%     
==========================================
  Files         167      167              
  Lines       63040    63056      +16     
==========================================
+ Hits        53674    53685      +11     
- Misses       9366     9371       +5     

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[MaxJPRey]

LGTM.

[Samuelopez-ansys]

LGTM

[SMoraisAnsys]

@Samuelopez-ansys @MaxJPRey Let's wait a bit before merging to see if the pyaedt-examples are not impacted. I'll open a PR to test that :)