Use qAsConst with non-const Qt containers in range-loops

... in various places

Change-Id: Ic6c0c1b9437a1ed402105c7a14a1f5f9454a68d4
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/coreplugin/statusbarmanager.cpp

@@ -113,7 +113,7 @@ static void createStatusBarManager()
         delete statusContext;
         // This is the catch-all on rampdown. Individual items may
         // have been removed earlier by destroyStatusBarWidget().
-        for (const QPointer<IContext> &context : m_contexts) {
+        for (const QPointer<IContext> &context : qAsConst(m_contexts)) {
             ICore::removeContextObject(context);
             delete context;
         }