Add :carton_shipped event

This adds a `:carton_shipped` event that is published whenever
`OrderShipping#ship` succeeds to mark a carton as shipped.

Co-Authored-By: Adam Mueller <[email protected]>

Author: benjaminwil

core/app/models/spree/order_shipping.rb

@@ -72,6 +72,7 @@ def ship(inventory_units:, stock_location:, address:, shipping_method:,
     @order.shipments.reload
     @order.recalculate
 
+    Spree::Bus.publish(:carton_shipped, carton:)
     carton
   end
 

core/lib/spree/core/engine.rb

@@ -61,6 +61,7 @@ class Engine < ::Rails::Engine
           Spree::Bus.clear
 
           %i[
+            carton_shipped
             order_canceled
             order_emptied
             order_finalized

core/spec/models/spree/order_shipping_spec.rb

@@ -85,6 +85,12 @@ def emails
       it "sets the external_number" do
         expect(subject.external_number).to eq 'some-external-number'
       end
+
+      it "publishes a 'carton_shipped' event" do
+        stub_spree_bus
+
+        expect(:carton_shipped).to have_been_published.with(carton: subject)
+      end
     end
 
     context "with a tracking number" do