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/languageclient/documentsymbolcache.cpp

@@ -64,7 +64,7 @@ void DocumentSymbolCache::requestSymbolsImpl()
         m_compressionTimer.start(200);
         return;
     }
-    for (const DocumentUri &uri : qAsConst(m_compressedUris)) {
+    for (const DocumentUri &uri : std::as_const(m_compressedUris)) {
         auto entry = m_cache.find(uri);
         if (entry != m_cache.end()) {
             emit gotSymbols(uri, entry.value());