Validate URI templates

[roblinksdata]

The csvwcheck.normalisation.InheritedProperties.normaliseUriTemplateProperty function validates aboutUrl, propertyUrl and valueUrl fields inside a CSV-W; these values should contain URI templates following the RFC6570 specification.

The code only validates that the value is a string, but could do more:

• Check that the URI template is valid according to the RFC6570 specification.
• Check that the variables used within the template are appropriate column names or standard variables defined in the CSV-W spec (see URI templates.