Fix data property dup

[Vagab]

When duping a property we can lose some attributes. So e.g.:

class Ex < Literal::Data
  prop :record, Book
end

record = Book.find(1)
ex = Ex.new(record:)
ex.record # => <Book id: nil>

because rails's dup does not preserve ids(and some other things)

cc @joeldrapper