Port from qAsConst() to std::as_const()

We've been requiring C++17 since Qt 6.0, and our qAsConst use finally
starts to bother us (QTBUG-99313), so time to port away from it
now.

Since qAsConst has exactly the same semantics as std::as_const (down
to rvalue treatment, constexpr'ness and noexcept'ness), there's really
nothing more to it than a global search-and-replace.

Task-number: QTBUG-99313
Change-Id: I88edd91395849574436299b8badda21bb93bea39
Reviewed-by: hjk <hjk@qt.io>

src/plugins/texteditor/refactoroverlay.cpp

@@ -25,7 +25,7 @@ RefactorOverlay::RefactorOverlay(TextEditor::TextEditorWidget *editor) :
 void RefactorOverlay::paint(QPainter *painter, const QRect &clip)
 {
     m_maxWidth = 0;
-    for (auto &marker : qAsConst(m_markers)) {
+    for (auto &marker : std::as_const(m_markers)) {
         paintMarker(marker, painter, clip);
     }