[FIX] website_sale: fixed display of variant informations in cart

Prior to this, even if your suggested or optional products were variants,
only the name of the template was shown.
Fixed GitHub issue 2746 and opw 614776

addons/website_sale/views/templates.xml

@@ -770,7 +770,7 @@
                   <td>
                       <div>
                           <a t-attf-href="/shop/product/#{ slug(product.product_tmpl_id) }">
-                              <strong t-field="product.name"/>
+                              <strong t-field="product.display_name"/>
                           </a>
                       </div>
                       <div class="text-muted" t-field="product.description_sale"/>

addons/website_sale_options/views/templates.xml

@@ -48,7 +48,7 @@
                   <span t-field="product.image_medium" t-field-options='{"widget": "image" }'/>
                 </td>
                 <td colspan="2">
-                  <strong t-field="product.name"/>
+                  <strong t-field="product.display_name"/>
                   <div class="text-muted">
                     <div t-field="product.description_sale"/>
                     <div class="js_attributes"/>