Calculate link to allow Nexedi developers access the ERP5 fields, forms and form actions from it.

* erp5 form gadget handle links to access from and form action
* label field gadget handle links to access field configuration, title
and descriptions translations
* page action handle all links to access workflows and portal type document
* add generic function to merge action with raw actions by group

* Add sample of action that allow uses access slideshow from ERP5JS