[FIX] website_sale: Pass website_sale_order to the template on each checkout step

The template `wizard_checkout` uses the `website_sale_order` to render the checkout process pages

But this values isn't passed to the template on these staps:
- /shop/checkout/
- /shop/address/

addons/website_sale/controllers/main.py

@@ -599,6 +599,7 @@ class WebsiteSale(http.Controller):
         country = 'country_id' in values and values['country_id'] != '' and request.env['res.country'].browse(int(values['country_id']))
         country = country and country.exists() or def_country_id
         render_values = {
+            'website_sale_order': order,
             'partner_id': partner_id,
             'mode': mode,
             'checkout': values,
@@ -627,6 +628,8 @@ class WebsiteSale(http.Controller):
 
         values = self.checkout_values(**post)
 
+        values.update({'website_sale_order': order})
+
         # Avoid useless rendering if called in ajax
         if post.get('xhr'):
             return 'ok'