Redefine PrefsPanel::Registration with new Registry system...

... preserving the existing ordering of pages with a combination of
preferences and ordering hints

src/prefs/ModulePrefs.cpp

@@ -191,12 +191,16 @@ void ModulePrefs::SetModuleStatus(const FilePath &fname, int iStatus){
 
 #ifdef EXPERIMENTAL_MODULE_PREFS
 namespace{
-PrefsPanel::Registration sAttachment{ 220,
+PrefsPanel::Registration sAttachment{ "Module",
    [](wxWindow *parent, wxWindowID winid, AudacityProject *)
    {
       wxASSERT(parent); // to justify safenew
       return safenew ModulePrefs(parent, winid);
-   }
+   },
+   false,
+   // Register with an explicit ordering hint because this one is
+   // only conditionally compiled
+   { "", { Registry::OrderingHint::After, "Mouse" } }
 };
 }
 #endif