QmlProject: Move RunConfigurationFactory close to RunConfiguration

No need to have a dozen lines of code in a separate translation
unit and more in line with what others do nowadays.

Change-Id: I765535d1484805bc3005fe23bfd4992a96a80e9c
Reviewed-by: hjk <hjk@qt.io>

src/plugins/qmlprojectmanager/qmlprojectrunconfiguration.h

@@ -86,4 +86,13 @@ private:
     QString m_qmlViewerArgs;
 };
 
+namespace Internal {
+
+class QmlProjectRunConfigurationFactory : public ProjectExplorer::FixedRunConfigurationFactory
+{
+public:
+    QmlProjectRunConfigurationFactory();
+};
+
+} // namespace Internal
 } // namespace QmlProjectManager