Respect styles translated to WS_EX_XXX in wxMSW wxCheckBox and wxRadioButton.

Take into account the window styles that translate to extended Windows styles
at MSW level.

Also override MSWGetStyle() in these classes, just as in most (all?) other
ones, for consistency instead of doing wx-to-MSW styles translation directly
in Create().

Notice that as a side effect of this change, border styles now work for
wxCheckBox which wasn't the case before. It's not clear if this is really
wanted but OTOH there doesn't seem to be any real reason to forbid them
neither.

Closes #14674.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72538 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/checkbox.h

@@ -55,6 +55,9 @@ public:
     // make the checkbox owner drawn or reset it to normal style
     void MSWMakeOwnerDrawn(bool ownerDrawn);
 
+    // implementation only from now on
+    virtual WXDWORD MSWGetStyle(long flags, WXDWORD *exstyle = NULL) const;
+
 protected:
     virtual wxSize DoGetBestSize() const;