erp5_base: adds the aggregate property on Career, to gather career related documents

bt5/erp5_base/PortalTypeBaseCategoryTemplateItem/base_category_list.xml

 <base_category_list>
+ <portal_type id="Career">
+  <item>aggregate</item>
+ </portal_type>
  <portal_type id="Currency Exchange Cell">
   <item>currency_exchange_type</item>
   <item>price_currency</item>

bt5/erp5_base/bt/template_portal_type_base_category_list

+Career | aggregate
 Currency Exchange Cell | currency_exchange_type
 Currency Exchange Cell | price_currency
 Currency Exchange Line | price_currency