Don't show error message if file added to qmlproject is picked up

Check for the case that a new file to be added to a .qmlproject
is also automatically covered e.g. by a wildcard filter. In this
case we don't have to do anything.

src/plugins/qmlprojectmanager/fileformat/qmlprojectitem.h

@@ -40,6 +40,7 @@ public:
     void setLibraryPaths(const QStringList &paths);
 
     QStringList files() const;
+    bool matchesFile(const QString &filePath) const;
 
 signals:
     void qmlFilesChanged();