Separate GUI functions from non-GUI functions in MaterialItemUtils

GUI/Models/GUIDomainSampleVisitor.cpp

GUI/Models/JobModelFunctions.cpp

GUI/Models/LayerItem.cpp

GUI/Models/MaterialItem.cpp

GUI/Models/MaterialItemUtils.cpp

GUI/Models/MaterialItemUtils.h

GUI/Models/MaterialModel.cpp

GUI/Models/MaterialPropertyController.cpp

GUI/Models/ParticleItem.cpp

GUI/Models/TransformToDomain.cpp

GUI/Views/MaterialEditor/MaterialEditorDialog.cpp

GUI/Views/MaterialEditor/MaterialEditorUtils.cpp

GUI/Views/MaterialEditor/MaterialEditorUtils.h

GUI/Views/PropertyEditor/CustomEditors.cpp

GUI/Views/PropertyEditor/TestComponentView.cpp

GUI/Views/SampleDesigner/DesignerHelper.cpp

GUI/Views/SampleDesigner/DesignerHelper.h

GUI/Views/SampleDesigner/SampleToolBar.cpp

Tests/UnitTests/GUI/TestMaterialModel.cpp

Tests/UnitTests/GUI/TestMaterialPropertyController.cpp