Make datasets listing API to list GRANTED tables from other org users

[alrocar]

Related issue

There are certain OAuth apps in which a number of datasets are managed by the org admin and then granted to the rest of the users of the organization.

Those datasets are not listed by api/v4/datasets thus an OAuth app does not know about them when requesting for the list of datasets of the user.

We might be able to reuse this method to get the list of granted tables to the user.

Also it would be necessary to:

• Add the schema to the response, since not all tables might be in the user schema
• Add the grants to the table (read [r] or read/write [rw])

Related issue

[gonzaloriestra]

Closing in favor of https://app.clubhouse.io/cartoteam/story/83456/make-datasets-listing-api-to-list-granted-tables-from-other-org-users