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/coreplugin/dialogs/saveitemsdialog.cpp

@@ -144,7 +144,7 @@ void SaveItemsDialog::adjustButtonWidths()
         possibleTexts << tr("Save Selected");
     int maxTextWidth = 0;
     QPushButton *saveButton = m_buttonBox->button(QDialogButtonBox::Save);
-    for (const QString &text : qAsConst(possibleTexts)) {
+    for (const QString &text : std::as_const(possibleTexts)) {
         saveButton->setText(text);
         int hint = saveButton->sizeHint().width();
         if (hint > maxTextWidth)