Parcel Ownership Support

[ingalls]

Context

This PR is a sketch of what Parcel Ownership could look like if it was tracked as a source attribute

{
    "type": "geojson",
    "pid": "ARN",
    "owners": {
        "function": "array",
        "fields": [
            [ "fname", "lname"]
        ]
    }
}

[stefanb]

Note that due to privacy regulation in EU names are usually not publicly released as part of OpenData, but can be looked up with authorities. They may release the names and types of non-private-person entities (eg state, municipalities, companies...).