Solid material model testing framework

[aabrown100-git]

Current situation

Currently, solid material models (in the function get_pk2cc()) are tested only through full simulations. It's difficult to tell from simulation results if the material models are implemented correctly, and there are likely some bugs in get_pk2cc(). See additional discussion in issue #150

Release Notes

• Expands the solid material model testing framework established in Add first unit test #150. The developer needs only to implement the strain energy density function $\Psi(\mathbf{F})$, where $\mathbf{F}$ is the deformation gradient tensor. Then, the 2nd Piola-Kirchhoff stress $\mathbf{S} = \frac{\partial \Psi}{\partial \mathbf{E}}$ and the material elasticity tensor $\mathbb{C} = \frac{\partial \mathbf{S}}{\partial \mathbf{E}}$ are tested using finite differences, for prescribed and random $\mathbf{F}$.
• Currently, the NeoHookean, Mooney-Rivlin, and Holzapfel-Ogden material models are tested
• Also, added some linear algebra functions in mat_fun_carray.h
• Also, fixed small bugs in Mooney-Rivlin elasticity tensor (see mat_models_carray.h) and in reading Mooney-Rivlin parameters (see set_material_props.h)

Documentation

I have included instructions in test.h for adding material models to the testing suite.

Testing

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

The code itself is testing.

Code of Conduct & Contributing Guidelines

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

[MatteoSalvador]

Really nice job @aabrown100-git! This looks good to me