REFACTOR: Import nastran extension and tests

[SMoraisAnsys]

Description

Refactoring of the import nastran extension where the extension has been updated to allow testing with tkinter direct interaction.

Issue linked

Associated to #6228

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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[Samuelopez-ansys]

Maybe instead of using os.path, we could use pathlib?

[SMoraisAnsys]

Maybe instead of using os.path, we could use pathlib?

Sure

[codecov]

Codecov Report

Attention: Patch coverage is 91.30435% with 8 lines in your changes missing coverage. Please review.

Project coverage is 85.20%. Comparing base (5bc3a10) to head (927109d).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6227      +/-   ##
==========================================
- Coverage   85.20%   85.20%   -0.01%     
==========================================
  Files         170      170              
  Lines       64209    64332     +123     
==========================================
+ Hits        54711    54815     +104     
- Misses       9498     9517      +19     

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[Samuelopez-ansys]

@SMoraisAnsys Great job! I like it a lot, should we also test

root.nametowidget("preview_button").invoke()?

Or the toogle theme? Maybe we could add another test for this common funcionalities?

I was thinking that maybe in a next PR, we could create a class to define the default UI, because then maybe we can start creating method to building common stuff like multitabs, buttons... following the same structure, what do you think?

[SMoraisAnsys]

@SMoraisAnsys Great job! I like it a lot, should we also test

root.nametowidget("preview_button").invoke()?

Or the toogle theme? Maybe we could add another test for this common funcionalities?

I was thinking that maybe in a next PR, we could create a class to define the default UI, because then maybe we can start creating method to building common stuff like multitabs, buttons... following the same structure, what do you think?

Maybe I'm missing something but the preview button and toggle button are tested in https://github.com/ansys/pyaedt/pull/6227/files#diff-ac52ccb11fa1ba48938746d6dbe8a83b26b7d455bb64077eee93ad579dd83161
Do you have something else in mind ?

I do agree with a follow-up PR where we create a defaut UI class. I'll handle it if that's ok with you