Add Carto datastore

[acouch]

Most catalogs have a concept of a datastore. Would like to use Carto for this. Files would get pushed using the Carto API. Once they are properly consumed or there is an error would retrieve this and add it to the document. For POD schema we would want to push this to the "Access Link" in the "distribution" collection.

Would also want mechanism to do this on file updates.

Issue Type

• Bug (https://github.com/interra/catalog-generate/blob/master/CONTRIBUTING.md#bug-reports)
• Feature (https://github.com/interra/catalog-generate/blob/master/CONTRIBUTING.md#feature-requests)