Generate a temporary URL to download a document from firm id, investment entity id and document id supplied in the input parameter. The returned URL is a pre-signed URL from AWS S3, which has 10 minutes expiry. The URL provides a restricted access to download the requested file directly from AWS S3, which is Anduin's underlining document storage system. Attempts to use the URL after the expiry time will result in an AccessDenied error from AWS S3.