dirview example: Show file icons on Windows

Use QFileIconProvider from QtWidgets.

Pick-to: 6.0
Task-number: QTBUG-66177
Change-Id: I22db2f8671c64d90c45ff7160af9a6925d1cecea
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

examples/widgets/itemviews/dirview/main.cpp

@@ -76,6 +76,8 @@ int main(int argc, char *argv[])
         ? QString() : parser.positionalArguments().first();
 
     QFileSystemModel model;
+    QFileIconProvider iconProvider;
+    model.setIconProvider(&iconProvider);
     model.setRootPath("");
     if (parser.isSet(dontUseCustomDirectoryIconsOption))
         model.setOption(QFileSystemModel::DontUseCustomDirectoryIcons);