Prepare or resume Checkout and return an authorized redirect

curl -X POST "https://example.com/v1/workplace/billing/checkout" \
  -H "Content-Type: application/json" \
  -d '{
    "id": "497f6eca-6276-4993-bfeb-53cbbbba6f08"
  }'

{
  "purchase": {
    "id": "497f6eca-6276-4993-bfeb-53cbbbba6f08",
    "state": "pending",
    "requestedAt": "2019-08-24T14:15:22Z",
    "expiresAt": "2019-08-24T14:15:22Z"
  },
  "action": {
    "kind": "checkout",
    "url": "http://example.com",
    "expiresAt": "2019-08-24T14:15:22Z"
  }
}