Changes to Download provider attachment

the response's body type changed from no type to object for status 200

deleted the header request parameter Authorization

the endpoint scheme security OAuthScheme was added to the API

for the query request parameter attachment_id, the type was generalized from no type to string, and format from no format to uuid

added the required property signed_download_url to the response with the 200 status

api operation id download_attachment removed and replaced with v3_download_attachment

endpoint added