Redeems a customer's loyalty points for a loyalty reward and creates a loyalty coupon.
Creating a loyalty coupon also creates a corresponding "reference" coupon with the Coupons API.
The customer receives the reference coupon, which they can apply to their order. The loyalty coupon and its corresponding reference coupon
are linked and the loyalty coupon's status reflects the current state of the reference coupon.
Check which loyalty rewards a site has available with List Rewards.
ID of the loyalty reward to redeem.