replace `eumd:DateTimeStamp` with standard datatype, remove `eu:URI`

[VladimirAlexiev]

Header-AP-Voc-RDFS2020.ttl defines non-standard datatypes:

eu:URI  rdf:type rdfs:Class ; cims:stereotype "European" , "Primitive" .
eumd:DateTimeStamp  rdf:type rdfs:Class ; cims:stereotype  "eumd" , "Primitive" .

This is similar to https://github.com/Sveino/Inst4CIM-KG/issues/27, but unlike profcim these Primitives are used:

md:Model.modelingAuthoritySet cims:dataType eu:URI ;
md:Model.profile cims:dataType eu:URI ;
dcat:startDate cims:dataType eumd:DateTimeStamp

It's better to replace with standard prop classes and datatypes:

md:Model.modelingAuthoritySet a owl:ObjectProperty.
md:Model.profile a owl:ObjectProperty.
dcat:startDate a owl:DatatypeProperty; rdfs:range xsd:dateTimeStamp.

I prefer to represent URLs as real URLs (object props without range) not literals. If you prefer literals, use this (but the only benefit of xsd:anyURI is that it allows URLs with invalid chars):

md:Model.modelingAuthoritySet a owl:DatatypeProperty; rdfs:range xsd:anyURI.
md:Model.profile a owl:DatatypeProperty; rdfs:range xsd:anyURI.
dcat:startDate a owl:DatatypeProperty; rdfs:range xsd:dateTimeStamp.

[Sveino]

Yes, we should definitely remove eumd:DataTimeStamp and eu.URI. I also prefer the use of owl:DatatypeProperty;

[griddigit-ci]

We will need to see what we add in CIM on this - in the domain

[VladimirAlexiev]

fix02-datatypes-74.ru