Make it possible to delete orders from the cart

jon/templates/entry/index.html

@@ -13,6 +13,7 @@
     <th>Steuergruppen-ID</th>
     <th>EK-Preis (Netto)</th>
     <th>VK-Preis (Brutto)</th>
+    <th>Aktionen</th>
   </tr>
   {% for cart_item in cart %}
   <tr>
@@ -24,6 +25,12 @@
     <td class="--align-right">{{ cart_item.tax_group_id }}</td>
     <td class="--align-right">{{ format_currency(cart_item.net_unit_price) }}</td>
     <td class="--align-right">{{ format_currency(cart_item.gross_unit_price) }}</td>
+    <td>
+      <form method="POST" action="/entry/delete-order">
+        <input type="hidden" name="order-index" value="{{ loop.index0 }}">
+        <button>Löschen</button>
+      </form>
+    </td>
   </tr>
   {% endfor %}
 </table>