QML Debugger refactoring

Now, QmlEngine creates the connection to the inferior (debuggee), and
notifies QmlInspector when a connection is established. Before,
inspector created the debugger engin, which was wrong.

QmlEngine's responsibilities are connecting to the debuggee and basic
QML/JS debugging features like locals & watchers, breakpoints etc.
QmlInspector takes care of Live Preview and other fancy inspection
features.

Reviewed-by: hjk

src/plugins/qmlprojectmanager/qmlprojectruncontrol.h

@@ -75,6 +75,9 @@ public:
     virtual ProjectExplorer::RunControl *create(ProjectExplorer::RunConfiguration *runConfiguration, const QString &mode);
     virtual QString displayName() const;
     virtual QWidget *createConfigurationWidget(ProjectExplorer::RunConfiguration *runConfiguration);
+
+private:
+    ProjectExplorer::RunControl *createDebugRunControl(QmlProjectRunConfiguration *runConfig);
 };
 
 } // namespace Internal