missing labels for Prez and alternates extension ontologies

[lalewis1]

See https://data.idnau.org/profiles/altr-ext:alt-profile for example.

• Ensure all resources are labelled appropriately.
• publish the labels to https://github.com/Kurrawong/semantic-background
• make the labels available to Prez by adding them to prez/reference_data/context_ontologies/

[lalewis1]

I've added labels for properties that I could see were missing at https://data.idnau.org/profiles/altr-ext:alt-profile
and have requested Davids help to fill out more labels.

[recalcitrantsupplant]

Does this cover everything? https://github.com/RDFLib/prez/blob/78fda6864d1e5593b9844bf35e9d86ac14024c2b/prez/reference_data/context_ontologies/prez-ontology.nq

We'd need to copy that file back to the maintenance v3 branch, but first add any missing properties/labels.

[lalewis1]

Missing labels added to maintenance-v3 in PR #242.