backoffice: apply form js to quick form preview (#53628)

wcs/admin/forms.py

@@ -1138,6 +1138,7 @@ class FormDefPage(Directory):
 
     def get_preview(self):
         form = Form(action='#', use_tokens=False)
+        form.attrs['data-backoffice-preview'] = 'on'
         on_page = 0
         for i, field in enumerate(self.formdef.fields):
             field.id = i

wcs/qommon/static/js/qommon.forms.js

@@ -335,7 +335,7 @@ $(function() {
 
   }
 
-  add_js_behaviours($('form[data-live-url]'));
+  add_js_behaviours($('form[data-live-url], form[data-backoffice-preview]'));
 
   // Form with error
   const first_widget_with_error = document.querySelector('.widget-with-error');