[#3826] Streamline handling of links in email templates

src/oscar/apps/checkout/mixins.py

             # We don't care that much if we can't resolve the URL
             pass
         else:
+            ctx['status_path'] = path
+
+            # status_url is deprecated, see https://github.com/django-oscar/django-oscar/issues/3826
             site = Site.objects.get_current(self.request)
             ctx['status_url'] = 'http://%s%s' % (site.domain, path)
         return ctx

src/oscar/templates/oscar/communication/emails/commtype_order_placed_body.html

 {% extends "oscar/communication/emails/base.html" %}
-{% load currency_filters i18n %}
+{% load currency_filters i18n url_tags %}
 
 {% block tbody %}
 <tr>
 {% if status_url %}
     <tr>
         <td class="content-block">
-            {% blocktrans %}You can view the status of this order by clicking <a href="{{ status_url }}" title="order status">here</a>{% endblocktrans %}
+            {% absolute_url site.domain status_path as absolute_status_url %}
+            {% blocktrans %}You can view the status of this order by clicking <a href="{{ absolute_status_url }}" title="order status">here</a>{% endblocktrans %}
         </td>
     </tr>
 {% endif %}

src/oscar/templates/oscar/communication/emails/commtype_order_placed_body.txt

-{% load currency_filters i18n %}{% blocktrans with order_number=order.number %}Hello,
+{% load currency_filters i18n url_tags %}{% blocktrans with order_number=order.number %}Hello,
 
 We are pleased to confirm your order {{ order_number }} has been received and
 will be processed shortly.{% endblocktrans %}
 {% endfor %}
 
 {% if status_url %}
+{% absolute_url site.domain status_path as absolute_status_url %}
 {% blocktrans %}You can view the status of this order at the below URL:
-{{ status_url }}{% endblocktrans %}
+{{ absolute_status_url }}{% endblocktrans %}
 {% endif %}
 
 {% blocktrans %}The team{% endblocktrans %}