El Salvador IBAN parsing rules

Examples

    iex>  %IbanEx.Iban{
    ...>    country_code: "SV",
    ...>    check_digits: "62",
    ...>    bank_code: "CENR",
    ...>    branch_code: nil,
    ...>    national_check: nil,
    ...>    account_number: "00000000000000700025"
    ...>  }
    ...>  |> IbanEx.Country.SV.to_string()
    "SV 62 CENR 00000000000000700025"