feat(payments): add order number to webhook payload

Include the order number in the webhook payload so consumers can
identify which order a payment notification belongs to.

Fixes #13858

app/services/payments/webhook_payload.rb

@@ -13,7 +13,7 @@ module Payments
         payment: @payment.slice(:updated_at, :amount, :state),
         enterprise: @enterprise.slice(:abn, :acn, :name)
           .merge(address: @enterprise.address.slice(:address1, :address2, :city, :zipcode)),
-        order: @order.slice(:total, :currency).merge(line_items: line_items)
+        order: @order.slice(:number, :total, :currency).merge(line_items: line_items)
       }.with_indifferent_access
     end
 
@@ -31,6 +31,7 @@ module Payments
 
     def self.test_order
       order = Spree::Order.new(
+        number: "R555555555",
         total: 0.00,
         currency: "AUD",
       )

spec/services/payments/webhook_payload_spec.rb

@@ -42,6 +42,7 @@ RSpec.describe Payments::WebhookPayload do
           }
         },
         order: {
+          number: order.number,
           total: order.total,
           currency: order.currency,
           line_items: line_items
@@ -72,6 +73,7 @@ RSpec.describe Payments::WebhookPayload do
           }
         },
         order: {
+          number: "R555555555",
           total: 0.00,
           currency: "AUD",
           line_items: [