Keep a pending late capture refund processing until PayPal confirms it

[rust-le]

Q	A
Branch?	phase-2-payment-requests
Bug fix?	yes
New feature?	no
BC breaks?	no
Related tickets	SY-884, follow-up to #812

A PENDING late capture refund was recorded as refunded and its Payment Request completed right away, unlike the payment refund (#812 (comment)). The PAYMENT.CAPTURE.REFUNDED webhook marked the late capture as refunded but never completed an open refund_late_capture Payment Request.

RefundPayPalLateCapturePaymentRequestHandler now handles the refund status like the payment refund: COMPLETED confirms it, PENDING keeps the Payment Request processing, anything else fails it. PayPalLateCaptureRefundConfirmationProcessor records the refund in the paypal_late_capture details and completes the processing refund_late_capture Payment Request; the handler and the webhook both use it.