Add custom fields to invoice, odergroup, supplier and user

app/views/admin/workgroups/_form.html.haml

@@ -2,6 +2,7 @@
   %p= t('.first_paragraph', url: link_to(t('.here'), new_invite_path(id: @workgroup.id), remote: true)).html_safe
 = simple_form_for [:admin, @workgroup] do |f|
   - captured = capture do
+    = render 'shared/custom_form_fields', f: f, type: :workgroup
     %h4= t 'admin.access_to'
     = f.input :role_suppliers
     = f.input :role_article_meta