Use constexpr kelvin_vector_dimensions function.

MaterialLib/MPL/Properties/EmbeddedFracturePermeability.h

MaterialLib/MPL/Utils/GetSymmetricTensor.h

MaterialLib/SolidModels/Ehlers.cpp

MaterialLib/SolidModels/Ehlers.h

MaterialLib/SolidModels/LinearElasticIsotropic.h

MaterialLib/SolidModels/LinearElasticIsotropicPhaseField.h

MaterialLib/SolidModels/LinearElasticOrthotropic.cpp

MaterialLib/SolidModels/LinearElasticOrthotropic.h

MaterialLib/SolidModels/Lubby2.cpp

MaterialLib/SolidModels/Lubby2.h

MaterialLib/SolidModels/MFront/MFront.cpp

MathLib/KelvinVector.h

ProcessLib/Deformation/BMatrixPolicy.h

ProcessLib/Deformation/LinearBMatrix.h

ProcessLib/HydroMechanics/CreateHydroMechanicsProcess.cpp

ProcessLib/HydroMechanics/HydroMechanicsFEM-impl.h

ProcessLib/HydroMechanics/HydroMechanicsFEM.h

ProcessLib/HydroMechanics/HydroMechanicsProcess.cpp

...essLib/LIE/HydroMechanics/CreateHydroMechanicsProcess.cpp

...anics/LocalAssembler/HydroMechanicsLocalAssemblerMatrix.h