Automatically check edited return items in RMA form

This feature got lost with solidusio#3565. It automatically checks rows
where the admin changes something, under the assumption that,
if a value is changed, then the user means to include the row
into the RMA/return.

An integration spec is added to properly track this feature.

backend/app/assets/javascripts/spree/backend/views/tables/return_items.js

@@ -4,6 +4,11 @@ Spree.Views.Tables.ReturnItems = Backbone.View.extend({
       var tfoot = document.createElement('tfoot')
       new Spree.Views.Tables.SelectableTable.SumReturnItemAmount({el: tfoot, model: this.model});
       this.$el.append(tfoot);
+
+      this.$el.find('input, select').not('.add-item').on('change', function(e) {
+        $(this).closest('tr').find('input.add-item').prop('checked', true)
+          .change();
+      });
     }
   },
 })

backend/spec/features/admin/orders/return_authorizations_spec.rb

@@ -27,7 +27,7 @@
   end
 
   context "when the user can manage return authorizations" do
-    describe "create" do
+    describe "create", :js do
       def create_return_authorization
         find("#select-all").click
         select "NY Warehouse", from: "Stock Location"
@@ -38,13 +38,19 @@ def create_return_authorization
         visit spree.new_admin_order_return_authorization_path(order)
       end
 
-      it "creates a return authorization", :js do
+      it "creates a return authorization" do
         create_return_authorization
 
         expect(page).to have_content "Return Authorization has been successfully created!"
       end
 
-      it "disables the button at submit", :js do
+      it "automatically checks edited rows" do
+        expect do
+          find(".refund-amount-input").native.send_keys [1, :tab]
+        end.to change { find(".add-item").checked? }.from(false).to(true)
+      end
+
+      it "disables the button at submit" do
         page.execute_script "$('form').submit(function(e) { e.preventDefault()})"
 
         create_return_authorization