Newly added qml files under project content (My Components) should be usable in the scene without reloading project

Whenever a there is an addition of a qml file under the project content folder (i.e. "My Components" types), the type represented by the qml file should become available to use as ModelNode without needing to reload the project. Similarly, if the qml file is removed, the existing ModelNodes of the type should become invalid.

Example use case for adding a type:

• Create a new MyRectangle.qml file in the project content folder.
• Add MyRectangle node into the scene.

--> MyRectange node appears in navigator without any warning and works correctly.