[web/views] avoid propagation of NoSelectableObject in some case of inlined relations / permissions When selecting an inlined creation form, we should catch the NoSelectable exception that will be raised if the user cannot add entities of the target type (this is not and cannot be verified earlier) or if some other custom selector prevents the form from being selected. Closes #6510921

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/* override settings in jquery.treeview.css */

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.treeview .placeholder { display: none; }