Run a multi-model comparison (async)

curl --request POST \
  --url https://api.rimp.io/v1/comparisons \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "prompt": "<string>",
  "models": [
    "<string>"
  ],
  "params_shared": {}
}
'

{
  "id": "<string>",
  "prompt": "<string>",
  "params_shared": {},
  "reserved_credits": 123,
  "created_at": "2023-11-07T05:31:56Z",
  "finished_at": "2023-11-07T05:31:56Z",
  "generations": [
    {
      "id": "<string>",
      "model": "<string>",
      "status": "<string>",
      "charged_credits": 123,
      "refunded_credits": 123,
      "error_code": "<string>",
      "outputs": [
        {
          "id": "<string>",
          "mime": "<string>",
          "width": 123,
          "height": 123,
          "duration_s": "<string>",
          "url": "<string>"
        }
      ]
    }
  ]
}