Qml Debugger: Enable debugging qml+cpp standalone applications

A new debugger engine, QmlCppEngine, is introduced, which wraps gdb
and qml engines into one. Alternatively, if using Windows, Cdb is used
instead of Gdb.

Most of the debugger ui switcher is now rewritten, and it is tailored
for the QML and CPP layout case, the only one supported anyway.

Reviewed-by: hjk

src/plugins/debugger/qml/qmlengine.h

@@ -63,6 +63,11 @@ public:
     explicit QmlEngine(const DebuggerStartParameters &startParameters);
     ~QmlEngine();
 
+    void setAttachToRunningExternalApp(bool value);
+    void shutdownInferiorAsSlave();
+    void shutdownEngineAsSlave();
+    void pauseConnection();
+
 public slots:
     void messageReceived(const QByteArray &message);
     void disconnected();
@@ -119,15 +124,18 @@ private slots:
     void connectionError();
 
 private:
-
     void expandObject(const QByteArray &iname, quint64 objectId);
     void sendPing();
 
 private:
+    friend class QmlCppEngine;
+
     int m_ping;
     QmlAdapter *m_adapter;
     ProjectExplorer::ApplicationLauncher m_applicationLauncher;
     bool m_addedAdapterToObjectPool;
+    bool m_attachToRunningExternalApp;
+    bool m_hasShutdown;
 };
 
 } // namespace Internal