Fixed AddToCart duplication when other plugins clone cart

[StyleT]

Changes proposed in this Pull Request:

Other plugins often clone Woocommerce cart to do various "on the fly" calculations and now this causes duplication of the AddToCart server events.

This fixes it once and forever ;)

fixes #2544

Screenshots:

How it looks before fix:

Detailed test instructions:

How to reproduce in tests

$cart = clone WC()->cart;
$cart->add_to_cart( $product_id, $qty, $variation_id, $variation )

Real-life test

Install this plugin and woo-stripe-payment as an example. Observe the following stack traces:

2023-09-16T17:51:06+00:00 DEBUG AddToCart: #0 /wp-includes/class-wp-hook.php(312): WC_Facebookcommerce_EventsTracker->inject_add_to_cart_event()
#1 /wp-includes/class-wp-hook.php(334): WP_Hook->apply_filters()
#2 /wp-includes/plugin.php(517): WP_Hook->do_action()
#3 /wp-content/plugins/woocommerce/includes/class-wc-cart.php(1279): do_action()
#4 /wp-content/plugins/woo-stripe-payment/includes/controllers/class-wc-stripe-controller-cart.php(275): WC_Cart->add_to_cart()
#5 /wp-includes/rest-api/class-wp-rest-server.php(1188): WC_Stripe_Controller_Cart->cart_calculation()
#6 /wp-includes/rest-api/class-wp-rest-server.php(1035): WP_REST_Server->respond_to_request()
#7 /wp-includes/rest-api/class-wp-rest-server.php(447): WP_REST_Server->dispatch()
#8 /wp-includes/rest-api.php(418): WP_REST_Server->serve_request()
#9 /wp-content/plugins/woo-stripe-payment/includes/class-wc-stripe-rest-api.php(159): rest_api_loaded()
#10 /wp-includes/class-wp-hook.php(310): WC_Stripe_Rest_API->process_frontend_request()
#11 /wp-includes/class-wp-hook.php(334): WP_Hook->apply_filters()
#12 /wp-includes/plugin.php(517): WP_Hook->do_action()
#13 /wp-content/plugins/woocommerce/includes/class-wc-ajax.php(96): do_action()
#14 /wp-includes/class-wp-hook.php(310): WC_AJAX::do_wc_ajax()
#15 /wp-includes/class-wp-hook.php(334): WP_Hook->apply_filters()
#16 /wp-includes/plugin.php(517): WP_Hook->do_action()
#17 /wp-includes/template-loader.php(13): do_action()
#18 /wp-blog-header.php(19): require_once('/var/www/html/u...')
#19 /index.php(17): require('/var/www/html/u...')
#20 {main}

Changelog entry

Fix - AddToCart duplication when other plugins clone cart

[ibndawood]

Thank you, @StyleT, for your contribution. We'll have this PR reviewed by our team as soon as possible.

[rawdreeg]

Code is good, and thanks for your contribution. Just a coding style related issue to be fixed before we can merge this.

[rawdreeg]

Hi @StyleT,

I have dropped a few review comments. Let us know if you have any questions.

Update: I committed then suggestion, I will proceed with merging this.

Thanks.
R