Test Linear Elastic Model and Remove Redundancy

[divyaadil23]

Problem

There seem to be 2 options for the linear elastic model - phys_lElas and stIso_LS. Neither of them have any test cases.

Solution

Look at how the two models are different, and combine them into a single model. Add unit tests and/or integration tests.

Additional context

No response

Code of Conduct

• I agree to follow this project's Code of Conduct and Contributing Guidelines

[ktbolt]

@divyaadil23 phys_lElas is an equation type, stIso_LS is a material model.

There are tests here for phys_lElas.

I believe that the stIso_LS material model is used for the mesh equation type.

[mrp089]

The linear elasticity test cases are still missing in #95 and stIso_LS is not covered. It would be nice if we could finally close that. @divyaadil23 do you want to add those as a first step?

As @ktbolt said, we use a linear elastic material for mesh deformation in ALE-FSI. It looks like the mesh equation type uses its own linear elastic material model that is covered.