Generic OpenAPI Wrapper for REST APIs

[kiwicopple]

We could use an OpenAPI spec, which many REST services expose as a JSON endpoint:

    create server example_api
      foreign data wrapper example_api_wrapper
      options (
        open_api_url 'https://api.example.com/'
      );

Then we'd map:

    GET -> SELECT (which would map selected columns into a table)
    POST -> INSERT
    PATCH -> UPDATE
    DELETE -> DELETE