elm_menu: mirgrate to the new focus

this just means the menu is registering a new manager, it is not really
doing anything, its just there so the children which are searching for
one are finiding one. Elm menu has not handled anything with keys in the
past and will later learn to do so.

src/lib/elementary/elm_menu.c

@@ -806,6 +806,16 @@ _elm_menu_efl_object_constructor(Eo *obj, Elm_Menu_Data *sd)
 {
    Eo *parent = NULL;
 
+   {
+      Efl_Ui_Focus_Manager *manager;
+
+      manager = efl_add(EFL_UI_FOCUS_MANAGER_CLASS, NULL,
+        efl_ui_focus_manager_root_set(efl_added, obj)
+      );
+
+      efl_composite_attach(obj, manager);
+   }
+
    obj = efl_constructor(efl_super(obj, MY_CLASS));
    efl_canvas_object_type_set(obj, MY_CLASS_NAME_LEGACY);
    evas_object_smart_callbacks_descriptions_set(obj, _smart_callbacks);

src/lib/elementary/elm_menu.eo

@@ -1,5 +1,5 @@
 class Elm.Menu (Elm.Widget, Efl.Ui.Clickable, Efl.Ui.Menu,
-                Elm.Interface.Atspi.Selection)
+                Elm.Interface.Atspi.Selection, Efl.Ui.Focus.Manager)
 {
    [[Elementary menu class]]
    legacy_prefix: elm_menu;