i18n: fix enum values for Dossier.state

According to Rails i18n guide, enum values should be localized
as `<model>/<enum>`, not as sub-values to the attribute.

This fixes an exception in administrate when displaying a Dossier
in the Manager.

Note: we need to change the way GraphQL attributes are generated, because
`AASM::Core::State#display_name` doesn’t honor the `model/attribute.value`
convention (and instead tries to localize as `model.attribute/value`).
So instead we lookup the localized name using ActiveRecord.

app/graphql/schema.graphql

@@ -1088,7 +1088,7 @@ enum DossierState {
   refuse
 
   """
-  Sans suite
+  Classé sans suite
   """
   sans_suite
 }