Somalia IBAN parsing rules

Examples

    iex>  %IbanEx.Iban{
    ...>    country_code: "SO",
    ...>    check_digits: "21",
    ...>    bank_code: "1000",
    ...>    branch_code: "001",
    ...>    national_check: nil,
    ...>    account_number: "001000100141"
    ...>  }
    ...>  |> IbanEx.Country.SO.to_string()
    "SO 21 1000 001 001000100141"