Faults: Use "Cell behind" when showing grid cells

When any grid cell visualization we need to set the Faults face mode to
the cell behind, to match the needs of the normal grid cell
visualization.
The face culling option is grayed out, but is not altered yet.

ApplicationCode/ModelVisualization/RivFaultPartMgr.cpp

@@ -653,8 +653,23 @@ caf::FaceCulling RivFaultPartMgr::faceCullingMode() const
                 return caf::FC_BACK;
             }
         }
+        else
+        {
+             return caf::FC_NONE;
+        }
+    }
+    else
+    {
+        // Always show cell behind fault if we are in grid visualization mode
+        if (m_grid->mainGrid()->faceNormalsIsOutwards())
+        {
+            return caf::FC_BACK;
+        }
+        else
+        {
+            return caf::FC_FRONT;
+        }
     }
-    return caf::FC_NONE;
 }
 
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