[HT/THM] Pass porosity via the variable array to material properties

ProcessLib/HT/MonolithicHTFEM.h

@@ -145,6 +145,8 @@ public:
             auto const porosity =
                 medium.property(MaterialPropertyLib::PropertyType::porosity)
                     .template value<double>(vars, pos, t, dt);
+            vars[static_cast<int>(MaterialPropertyLib::Variable::porosity)] =
+                porosity;
 
             auto const intrinsic_permeability =
                 MaterialPropertyLib::formEigenTensor<GlobalDim>(

ProcessLib/HT/StaggeredHTFEM-impl.h

@@ -238,6 +238,8 @@ void StaggeredHTFEM<ShapeFunction, IntegrationMethod, GlobalDim>::
         auto const porosity =
             medium.property(MaterialPropertyLib::PropertyType::porosity)
                 .template value<double>(vars, pos, t, dt);
+        vars[static_cast<int>(MaterialPropertyLib::Variable::porosity)] =
+            porosity;
 
         // Use the fluid density model to compute the density
         auto const fluid_density =

ProcessLib/ThermoHydroMechanics/ThermoHydroMechanicsFEM-impl.h

@@ -247,6 +247,8 @@ void ThermoHydroMechanicsLocalAssembler<ShapeFunctionDisplacement,
         auto const porosity =
             medium->property(MaterialPropertyLib::PropertyType::porosity)
                 .template value<double>(vars, x_position, t, dt);
+        vars[static_cast<int>(MaterialPropertyLib::Variable::porosity)] =
+            porosity;
 
         auto const alpha =
             medium