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.
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