Start a PDF upload for a handout: returns a presigned PUT straight to S3 (the web proxy caps request bodies at 10 MB). Follow with `POST {id}/handout/versions`.

Ask for somewhere to upload a handout PDF (ITE-1474).

A presigned PUT straight to S3 (the web proxy caps bodies at 10 MB). The browser must send Content-Type: application/pdf, which is signed into the URL, then call confirm with string InitHandoutUploadResponse.UploadId and the same file name.