B bar method for linear deformation

As titled, this MR presents the implementation of the B bar method for linear deformation.

To verify the implementation of the B bar method, the so called Cook's membrane is used as a benchmark. Illustrated in the following figure, this example simulates a tapered and swept panel of unit thickness. The left edge is clamped and the right edge is applied with a distributed shearing load

F

= 100 N/mm. The plane strain condition is considered. This numerical model is exactly the same as that is presented in the paper by T. Elguedj et al.

The following figure shows that the convergence of the solutions obtained by using the B bar method is the the same as what presented in the paper by T. Elguedj et al [1]. However, the results obtained without the B bar method are quit far from the converged solution at the finest mesh.

Note: Jupter Notebook test will come in the following MR due to a CI issue: the ogs built in CI is not used in the corresponding Python wheel for the Jupter Notebook test.

1. Feature description was added to the changelog
2. Tests covering your feature were added?
3. Any new feature or behaviour change was documented?