Generate presigned URL for object operations

curl --request POST \
  --url https://api.case.dev/vault/{id}/objects/{objectId}/presigned-url \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "operation": "GET",
  "expiresIn": 3600,
  "contentType": "<string>",
  "sizeBytes": 2684354560
}
'

{
  "objectId": "<string>",
  "vaultId": "<string>",
  "filename": "<string>",
  "s3Key": "<string>",
  "operation": "<string>",
  "presignedUrl": "<string>",
  "expiresIn": 123,
  "expiresAt": "2023-11-07T05:31:56Z",
  "instructions": {},
  "metadata": {
    "contentType": "<string>",
    "sizeBytes": 123,
    "bucket": "<string>",
    "region": "<string>"
  }
}