Calculate total_displacement in C++ instead of python. As this happens for every node in every time step, which can be a performance bottleneck The work should be similar to "`CalculateIncrementalDisplacementProcess`". Needs: - [ ] Unit testing - [ ] Documentation - [ ] (At least) one integration test - [ ] Remove the Python code - [ ] Double-check the SolverStrategyWrapper (see if it's duplicated)