For a given file id, return the file associated with that Id.
The complete URL required to fetch the uploaded file can be found in the submitted form metadata, or on an associated contact record. The name of the property containing this URL will vary depending on the name given to the file upload.
The initial GET on this URL returns a redirect, which should be followed to retrieve the file.
Specific URL parameters, including portalId, sign, conversionId, and filename will be included as part of the URL fetched from the property as described above. These variables should not be changed.