QmlProjectManager: Fix compilation with latest changes of QDeclarative

All files have been renamed from Qml to QDeclarative.
Registration of types is now done in an initializer method.

src/plugins/qmlprojectmanager/fileformat/qmlprojectfileformat.h

@@ -0,0 +1,13 @@
+#ifndef QMLPROJECTFILEFORMAT_H
+#define QMLPROJECTFILEFORMAT_H
+
+namespace QmlProjectManager {
+
+class QmlProjectFileFormat {
+public:
+    static void registerDeclarativeTypes();
+};
+
+} // namespace QmlProjectManager
+
+#endif // QMLPROJECTFILEFORMAT_H