Add wxRibbonBar::DeletePage() and ClearPages() methods.

Also add a trivial GetPageCount() helper.

Closes #14437.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71888 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/ribbon/bar.h

@@ -113,8 +113,12 @@ public:
     bool SetActivePage(wxRibbonPage* page);
     int GetActivePage() const;
     wxRibbonPage* GetPage(int n);
+    size_t GetPageCount() const;
     bool DismissExpandedPanel();
 
+    void DeletePage(size_t n);
+    void ClearPages();
+
     void ShowPanels(bool show = true);
     void HidePanels() { ShowPanels(false); }
     bool ArePanelsShown() const { return m_arePanelsShown; }