PD: harmonize API of view provider classes

* add virtual method featureName() to ViewProviderTransformed
* add featureIcon() to ViewProviderTransformed and ViewProviderDressUp

src/Mod/PartDesign/Gui/ViewProviderMirrored.h

@@ -34,11 +34,12 @@ class PartDesignGuiExport ViewProviderMirrored : public ViewProviderTransformed
     PROPERTY_HEADER_WITH_OVERRIDE(PartDesignGui::ViewProviderMirrored);
 public:
     ViewProviderMirrored() {
-        featureName = std::string("Mirrored");
         menuName = tr("Mirrored parameters");
         sPixmap = "PartDesign_Mirrored.svg";
     }
 
+    const std::string & featureName() const override;
+
 protected:
     /// Returns a newly create dialog for the part to be placed in the task view
     TaskDlgFeatureParameters *getEditDialog() override;