Revisit taxonomies and "type" references
Fixed up the performance metric taxonomy (https://untp.unece.org/docs/specification/CoreTaxonomies#performance-metrics-1) :
- Removed the battery specific metrics because this should be a product independent metric vocabulary
- Fixed the missing vocabulary references by adding aggregationMethod and improvementDirection to UNTP core ontology.
- Added two new top level categories (product quality & safety, and food quality & safety) to accomodate performance metrics that are not only sustainability related.
- Fixed DPP samples that were using taxonomy terms that were removed.
Also in this PR - accomodating requests from Pat St-Louis and Nic Charaud to add "type" properties to object references throughout the UNTP schema and samples - so that it's simpler to process credentials and drop them in a graph in the right spot.