Remove magic number and hard type enums in ArrowPropEnum.h

- Remove currently present magic numbers
- Hard type enums, so magic numbers can no longer be introduced. We don't want people to introduce magic numbers.

src/Mod/TechDraw/Gui/ViewProviderDimension.cpp

@@ -85,7 +85,7 @@ ViewProviderDimension::ViewProviderDimension()
                                                                      "Arrow size in units");
 
     ArrowStyle.setEnums(ArrowPropEnum::ArrowTypeEnums);     // NOLINT
-    ADD_PROPERTY_TYPE(ArrowStyle, (PreferencesGui::dimArrowStyle()),
+    ADD_PROPERTY_TYPE(ArrowStyle, (static_cast<int>(PreferencesGui::dimArrowStyle())),
                                     group, (App::PropertyType)(App::Prop_None),
                                    "Arrow end symbol - point, filled arrow, etc");