Material: add workbench manipulator

Implement a workbench manipulator to inject Std_Material and Std_Appearance to (context) menu.

src/Mod/PartDesign/Gui/Workbench.cpp

@@ -237,14 +237,12 @@ void Workbench::setupContextMenu(const char* recipient, Gui::MenuItem* item) con
 
             if (Gui::Selection().countObjectsOfType(App::DocumentObject::getClassTypeId()) > 0) {
                 *item << "Std_Placement"
-                      << "Std_SetMaterial"
                       << "Std_ToggleVisibility"
                       << "Std_ShowSelection"
                       << "Std_HideSelection"
                       << "Std_ToggleSelectability"
                       << "Std_TreeSelectAllInstances"
                       << "Separator"
-                      << "Std_SetAppearance"
                       << "Std_RandomColor"
                       << "Std_ToggleTransparency"
                       << "Std_Cut"