Always use native task dialog for wxProgressDialog under MSW if supported.

Use task dialogs even for the dialogs with wxPD_AUTO_HIDE style flag and
without wxPD_CAN_ABORT one. Generic fallback was used in this case as native
task dialog doesn't support dialogs without buttons but it is finally better
to create a dummy button and use the native dialog nevertheless. We already
have a mostly disabled "Close" button for the dialogs without wxPD_AUTO_HIDE
style so it seems logical to also have it (but just never enable it at all)
when this style is used.

Closes #12462.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65574 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/progdlg.h

@@ -48,10 +48,6 @@ public:
     virtual void Update() { wxGenericProgressDialog::Update(); }
 
 private:
-    // Returns true if the task dialog is available. If not, all the methods of
-    // this class simply fall back to wxGenericProgressDialog versions.
-    bool HasNativeProgressDialog() const;
-
     // Performs common routines to Update() and Pulse(). Requires the
     // shared object to have been entered.
     bool DoNativeBeforeUpdate(bool *skip);