Record a refund of an order

Records money already returned to the guest outside this app (cash, card terminal, a till's own tenders); no payment provider is called, and imported orders are refused for Fortis to record. A guest's online MyFatoorah payment is never recorded here: it is refunded through payments.refundMyFatoorah. Refused with BAD_REQUEST and refusal refundThroughMyFatoorah when such a payment still has money to refund and the request names no amount, asks for more than the order's other payments hold, or sends an expectedRemainingCents that counts that payment. Each refunded payment's tip goes back with it, in the share of that payment refunded, posted as negative tip rows; the refunds that empty a payment return exactly the tip paid on it.