promote OP contains to SAREF core

Related to saref4bldg#13 (closed) saref4envi#18 (closed) saref-portal#9

SAREF4ENVI SAREF4BLDG SAREF4AGRI SAREF4EHAW all define an OP saref4abcd:contains

in SAREF core we have saref:consistsOf, but not saref:contains.

The suggestion is to introduce saref:contains at the level of features of interest and feature kinds, similar to saref:consistsOf

saref:contains a owl:ObjectProperty , owl:TransitiveProperty ;
    rdfs:comment "A relationship indicating that an entity contains another entity (e.g., a room that contains a temperature sensor)."@en ;
    rdfs:label "contains"@en .

saref:FeatureKind rdfs:subClassOf [ 
    a owl:Restriction ; 
    owl:onProperty saref:contains ; 
    owl:allValuesFrom saref:FeatureKind ] .

saref:FeatureOfInterest rdfs:subClassOf [ 
    a owl:Restriction ; 
    owl:onProperty saref:contains ; 
    owl:allValuesFrom saref:FeatureOfInterest ] .

Here, we do not align to GeoSPARQL. We leave GeoSPARQL for 2D SpatialObjects

We're still lacking a comparison to saref:consistsOf in the definition