fixup! erp5_trade: enable template creation for purchase order

also needs to be declared in hidden content types to prevent adding
directly in preferences

bt5/erp5_trade/PortalTypeHiddenContentTypeTemplateItem/hidden_content_type_list.xml

@@ -12,6 +12,7 @@
   <item>Inventory Cell</item>
  </portal_type>
  <portal_type id="Preference">
+  <item>Purchase Order</item>
   <item>Sale Order</item>
  </portal_type>
  <portal_type id="Purchase Order Line">

bt5/erp5_trade/bt/template_portal_type_hidden_content_type_list

@@ -2,6 +2,7 @@ Container Line | Container Cell
 Internal Order Line | Internal Order Cell
 Internal Packing List Line | Internal Packing List Cell
 Inventory Line | Inventory Cell
+Preference | Purchase Order
 Preference | Sale Order
 Purchase Order Line | Purchase Order Cell
 Purchase Packing List Line | Purchase Packing List Cell