Add wxRibbonButtonBar::GetItem(), GetItemById() and GetItemId().

Allow accessing the ribbon bar buttons either by index or ID.

See #14630.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72526 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/ribbon/buttonbar.h

@@ -126,6 +126,10 @@ public:
                 wxObject* client_data = NULL);
 
     virtual size_t GetButtonCount() const;
+    virtual wxRibbonButtonBarButtonBase *GetItem(size_t n) const;
+    virtual wxRibbonButtonBarButtonBase *GetItemById(int id) const;
+    virtual int GetItemId(wxRibbonButtonBarButtonBase *button) const;
+
 
     virtual bool Realize();
     virtual void ClearButtons();