Ustruct and volumetric material tests

[aabrown100-git]

Current situation

Material unit tests do not test ustruct material model implementations, nor volumetric penalty model implementations. #150

Release Notes

• Add/update comments in material testing code and in material model implementation code
• Add instructions for running material tests
• Add tests for ustruct material model implementations
• Add tests for volumetric penalty model implementations (for both struct and ustruct)
• Fix bug in ustruct HO model where PK2 stress was not being updated

Testing

Please ensure that the PR meets the testing requirements set by GitHub Actions.

This code itself is testing.

Code of Conduct & Contributing Guidelines

• I agree to follow the Code of Conduct and Contributing Guidelines.

[codecov]

Codecov Report

Attention: Patch coverage is 95.05208% with 19 lines in your changes missing coverage. Please review.

Project coverage is 65.72%. Comparing base (f424b7c) to head (69eed1b).

Files	Patch %	Lines
tests/unitTests/test.h	78.16%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #229      +/-   ##
==========================================
+ Coverage   64.96%   65.72%   +0.76%     
==========================================
  Files         116      116              
  Lines       29153    28876     -277     
==========================================
+ Hits        18938    18980      +42     
+ Misses      10215     9896     -319     

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[mrp089]

@aabrown100-git, I'm very happy you tackled testing the solid material models!

As someone who has messed up a test-PR before, I have one piece of wisdom: Do your tests fail if you change parts of the code that the test should be sensitive to ("test the test")? You can verify this locally.

Also, thank you for adding comments to your (and existing code)! You could slightly change their format and they would show up in Doxygen. There's a quick guide here (it's mostly converting to /// or @brief). There's also a plugin for VS Code that makes it very easy (probably for other editors as well).

[MatteoSalvador]

Thanks @mrp089 for your comments!
@aabrown100-git, once all the points raised by @mrp089 are addressed I will merge this PR!

[aabrown100-git]

@mrp089 Thanks for the comments!

• I was able to make all the tests fail, so I think the tests are tested :)
• I just modified many of the comments to cooperate with Doxygen.
• I responded to your other comments individually.