Debugger: Fix QByteArray/QString overload mixup

And take the opportunity to sprinkle more 'override' over the code.

Change-Id: I8b6b80653ca671e7681b7de2de5ad4288b281ccf
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/debugger/qml/qmlengine.h

@@ -45,7 +45,7 @@ class QmlEngine : public DebuggerEngine
 public:
     explicit QmlEngine(const DebuggerRunParameters &runParameters,
                        DebuggerEngine *masterEngine = nullptr);
-    ~QmlEngine();
+    ~QmlEngine() override;
 
     void filterApplicationMessage(const QString &msg, int channel) const;