Kebab::Convert::Enum(T)

Converter for Crystal enums. Enum-typed fields use it automatically. Naming it as a converter: is equivalent. Member names are matched with Enum.parse? (case-insensitive, -/_ equivalent), so MyEnum::ApprovalRequested accepts "approval_requested": https://crystal-lang.org/api/Enum.html#parse%28string%3AString%29%3Aself-class-method