Add support for WooCommerce Shipping Setting Enable debug mode

[bilfeldt]

If the setting WooCommerce->Settings->Shipping->Shipping options->Enable debug mode is enabled, then a bar with the matching shipping zone is shown during checkout and caching is disabled.

We should show how we calculated the shipping prices there as well. We are already showing how we calculate the shipping price in the error log, but it would be nice to show it there.

[bilfeldt]

This is a Nice to have feature, so let us first find out if this can be done easily.

[bilfeldt]

Basically this is how WooCommerce does it:

/**
 * Loads all shipping methods which are hooked in.
 * If a $package is passed some methods may add themselves conditionally and zones will be used.
 *
 * @param array $package Package information.
 * @return WC_Shipping_Method[]
 */
public function load_shipping_methods( $package = array() ) {
if ( ! empty( $package ) ) {
	$debug_mode             = 'yes' === get_option( 'woocommerce_shipping_debug_mode', 'no' );
	$shipping_zone          = WC_Shipping_Zones::get_zone_matching_package( $package );
	$this->shipping_methods = $shipping_zone->get_shipping_methods( true );
	// Debug output.
	if ( $debug_mode && ! defined( 'WOOCOMMERCE_CHECKOUT' ) && ! defined( 'WC_DOING_AJAX' ) && ! wc_has_notice( 'Customer matched zone "' . $shipping_zone->get_zone_name() . '"' ) ) {
		wc_add_notice( 'Customer matched zone "' . $shipping_zone->get_zone_name() . '"' );
	}
} else {
....

So when we add something to the log, then we can simply also add it using wc_add_notice() if the debug setting is enabled and then reuse the check they have:

$debug_mode = ('yes' === get_option( 'woocommerce_shipping_debug_mode', 'no' ));
if ( $debug_mode && ! defined( 'WOOCOMMERCE_CHECKOUT' ) && ! defined( 'WC_DOING_AJAX' ) ) {
    wc_add_notice($ss_log_entry);//This is where we add the log entry
}