Mongolia IBAN parsing rules

Examples

    iex>  %IbanEx.Iban{
    ...>    country_code: "MN",
    ...>    check_digits: "12",
    ...>    bank_code: "1234",
    ...>    account_number: "123456789123"
    ...>  }
    ...>  |> IbanEx.Country.MN.to_string()
    "MN 12 1234 123456789123"