Latvian IBAN parsing rules

Examples

    iex>  %IbanEx.Iban{
    ...>    country_code: "LV",
    ...>    check_digits: "80",
    ...>    bank_code: "BANK",
    ...>    branch_code: nil,
    ...>    national_check: nil,
    ...>    account_number: "0000435195001"
    ...>  }
    ...>  |> IbanEx.Country.LV.to_string()
    "LV 80 BANK 0000435195001"