Listing LoDs of parents and children

Currently if you load a multi-LoD dataset the parents are all loaded as LoD0 in the tree view. Perhaps it's better to summarise them as multi-LoD or something that is more indicative?

![image](https://user-images.githubusercontent.com/19203377/135243156-04ab0d4e-0a53-44f2-ab35-d9bd7b374281.png)