Request: search for label property in name space, not only in root of domain

[jipclaassens]

Currently, GeoDMS only looks for a label in the root of the domain. And if you configure a label in a derived domain, it is not being found.

In the case of reading from storage, it is unwanted to explicitly configure the label property there. For example, if you read a Geopackage with units in it. Then, you would have to configure the label attribute in the reading phase.

It would be better to look for a label in the inherited subitems, just like geometry.

[jipclaassens]

@jipclaassens maak code voorbeeld

[MaartenHilferink]

Fixed for case with /RegioIndelingen/Gemeente referring to GeoPackage for derived attributes