QmlProjectManager: Re-use folder "qml" icon overly from ProjectExplorer

The one in ProjectExplorer does the same except that it also has a @2x
variant, thus looks less ugly on HighDPI.

Change-Id: Ic6faa8fd48b73cfe0b94eba776433fa12b8e0b09
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmlprojectmanager/qmlproject.qrc

@@ -1,6 +1,5 @@
 <RCC>
     <qresource prefix="/qmlproject">
-        <file>images/qmlfolder.png</file>
         <file>images/qmlproject.png</file>
     </qresource>
 </RCC>

src/plugins/qmlprojectmanager/qmlprojectnodes.cpp

@@ -42,7 +42,7 @@ QmlProjectNode::QmlProjectNode(QmlProject *project) : ProjectNode(project->proje
 {
     setDisplayName(project->projectFilePath().toFileInfo().completeBaseName());
 
-    static QIcon qmlProjectIcon = Core::FileIconProvider::directoryIcon(QLatin1String(":/qmlproject/images/qmlfolder.png"));
+    static QIcon qmlProjectIcon = Core::FileIconProvider::directoryIcon(":/projectexplorer/images/fileoverlay_qml.png");
     setIcon(qmlProjectIcon);
 }