Anonymous Preprint server: fix withdraw process function

[melisabok]

Set the readers of the original note as content.authorids + OpenReview.net/Anonymous_Preprint. Remove the tilde id of the original user.

Ideally, it would be nice to move the setup of the server to the openreview-py library.

[melisabok]

The process function error:

"DEBUG: process accepted?: true",
"DEBUG: SUCCESS: GET http://localhost:3000/notes?id=IC0MaEviP7D",
"DEBUG: SUCCESS: POST http://localhost:3000/notes",
"DEBUG: SUCCESS: GET http://localhost:3000/notes?id=g9jyV6-M4kU",
"DEBUG: ERROR: POST http://localhost:3000/notes",
"DEBUG: RESPONSE: 400",
"DEBUG: BODY: {\"status\":400,\"name\":\"notMatch\",\"message\":\"NotMatch\",\"errors\":[{\"type\":\"notMatch\",\"path\":\"readers\",\"value\":[\"OpenReview.net/Anonymous_Preprint\",\"[email protected]\",\"[email protected]\",\"[email protected]\",\"~Sheikh_Azizul_Hakim1\"],\"path2\":\"invitation.reply.readers\",\"value2\":{\"description\":\"The users who will be allowed to read the above content.\",\"values-copied\":[\"OpenReview.net/Anonymous_Preprint\",\"{content.authorids}\",\"{signatures}\"]}}]}",
"INFO: DONE"

The function is trying to delete the Blind and Original submission, I believe that deleting the Bling submission automatically deletes the original.

Also it would be nice if a confirmation email is sent to the authors of the paper.