[Feature] Support currency conversion transaction

[dev590t]

Hi, I'm trying to import Wise bank statement.

Wise is a bank that support multi-currency account, this is a subset of columns of Wise csv, with a transaction in my EUR account, it convert 100 EUR to 107 USD:

| Amount | Currency | Exchange From | Exchange To | Exchange Rate Total fees | Exchange To | Amount |
|    100 | EUR      | EUR           | USD         |                     1.07 |        4.50 | 107.00 |

I expect to produce a OFX like that:

<STMTTRN>
  <TRNTYPE>DEBIT</TRNTYPE>
  <DTPOSTED>20231001000000</DTPOSTED>
  <TRNAMT>-107.00</TRNAMT> <!-- Converted amount in USD -->
  <FITID>123456</FITID>
  <NAME>Currency Conversion</NAME>
  <MEMO>EUR to USD conversion with fee</MEMO>
  <ORIGCURRENCY>
    <CURRATE>1.0700</CURRATE> <!-- Exchange rate -->
    <CURSYM>EUR</CURSYM>
    <CURAMT>-100.00</CURAMT> <!-- Original amount in EUR -->
  </ORIGCURRENCY>
</STMTTRN>
<STMTTRN>
  <TRNTYPE>FEE</TRNTYPE>
  <DTPOSTED>20231001000000</DTPOSTED>
  <TRNAMT>-4.50</TRNAMT> <!-- Fee amount in USD -->
  <FITID>123457</FITID>
  <NAME>Conversion Fee</NAME>
  <MEMO>Fee for EUR to USD conversion</MEMO>
</STMTTRN>

Then my double entry accounting tool can get the information from ORIGCURRENCY, and check balance of transaction is zero.

It seems csv2ofx doesn't support that.