QML Observer: Complain about not having it if debugging .qmlprojects

Reviewed-by: hjk

src/plugins/debugger/debuggerengine.h

@@ -84,6 +84,7 @@ public:
     quint16 qmlServerPort;
     QString projectBuildDir;
     QString projectDir;
+    bool qmlObserverAvailable;
     // for cpp+qml debugging
     DebuggerEngineType cppEngineType;
 
@@ -264,6 +265,7 @@ public:
     QString qtDumperLibraryName() const;
     QStringList qtDumperLibraryLocations() const;
     void showQtDumperLibraryWarning(const QString &details);
+    void showQmlObserverToolWarning();
 
     static const char *stateName(int s);