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