Account identification from <Acct> within a statement.
<Acct>
Either iban or other_id will be present; both may be nil for unusual account formats.
iban
other_id
@type t() :: %ISO20022.Camt053.Account{ currency: String.t() | nil, iban: String.t() | nil, name: String.t() | nil, other_id: String.t() | nil, other_scheme: String.t() | nil, servicer_bic: String.t() | nil }