Add wxTopLevelWindow::Enable{Maximize,Minimize}Button()

Allow to disable maximize and minimize buttons dynamically just as we already
allow to disable the "Close" button using EnableCloseButton().

Currently implemented for MSW and OSX only.

Closes #17133.

include/wx/msw/toplevel.h

@@ -68,6 +68,8 @@ public:
     // wxMSW only: EnableCloseButton(false) may be used to remove the "Close"
     // button from the title bar
     virtual bool EnableCloseButton(bool enable = true);
+    virtual bool EnableMaximizeButton(bool enable = true) wxOVERRIDE;
+    virtual bool EnableMinimizeButton(bool enable = true) wxOVERRIDE;
 
     // Set window transparency if the platform supports it
     virtual bool SetTransparent(wxByte alpha);