Add comparison script FreeFEM vs SOFA for 1D bar traction

[Fimache]

This PR adds a comparison script between FreeFEM and SOFA for a 1D bar traction problem.

• Runs FreeFEM simulation
• Runs SOFA simulation with the same mesh
• Compares results (L2 norm, max error)
• Generates displacement plots and error figure

Results

• SOFA and FreeFEM results match with very low error (~1e-4)
• Validates the SOFA implementation for 1D elasticity

[th-skam]

Setting this to WIP.
The current file in-lines the sofa and freefem files, writes them out then runs them.
We would like to keep everything running from one file and using the API of these software to run simulations and compare the results.

[th-skam]

This has become irrelevant as we were adding the comparisons as we were completing the work for 1-3D.
Close without a merge.