Legacy PayPal plug-in mod for zc v1.58A and php 8.1 (paypaldp.php, paypalwpp.php)

zc 1.58A with php 8.1

The original paypal files from 1.58A installer will cause some warnings when php version is 8.1. I copied the files from zen cart 2.01 and made some modifications, and they are working without warning now. If you like to try my code, here is my repo.

https://github.com/njcyx/paypal_legacy_zc

Some key notes:

1. convertToLocalTimeZone() function will trigger warnings under zen cart 1.58A. Changed the code back to the previous version.
2. In the past zc official updates, $order_amount is changed to $order->info['total']. Not sure if it also works under zen cart 1.58A, but I changed it back.
3. With paypaldp.php (credit card processing), order confirmation email will show auth code as n/a on the top. While in the previous zen cart, auth code is hidden. Updated the code to hide this section.
4. ipn_main_handler.php has no change (v2.0.0rc). It can be used directly.