Sets up default attributes and actions for resources extended with AshAuthentication.OidcConnection.

For each configured field (base_url_field, client_id_field, etc.), if the resource doesn't already define it (as an attribute, calculation, aggregate, or relationship), a default string attribute is built. Users can replace any field with a calculation (e.g. one that decrypts an encrypted column on load) by simply defining it on the resource.