wip(dossier_created_hook): add tile to administrateurs/procedure#show in order to crud dossier_created_hook
refactor(css.utilities): remove merge helpers.scss within utils.scss (same purpose). use scss each for spacer modifiers
refactor(dossiers/_merci.html): extract partial _merci so we can re-use it in preview of dossier_created_hook.
feat(wip): current progress
Context: we want to validate public and private types_de_champ
separately.
Before we validated the whole revision (and then validators themselves
enumerated all champs, public and private).
Now we validate the actual public types_de_champ, which will let us
validate separately the private types_de_champ.
