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/autotest/qtest/qttestparser.cpp

@@ -163,7 +163,7 @@ static CPlusPlus::Document::Ptr declaringDocument(CPlusPlus::Document::Ptr doc,
         }
     }
 
-    for (const CPlusPlus::LookupItem &item : qAsConst(lookupItems)) {
+    for (const CPlusPlus::LookupItem &item : std::as_const(lookupItems)) {
         if (CPlusPlus::Symbol *symbol = item.declaration()) {
             if (CPlusPlus::Class *toeClass = symbol->asClass()) {
                 const QString declFileName = QLatin1String(toeClass->fileId()->chars(),