[WC Compatibility] Deprecation notices since WooCommerce 9.3 related to the Navigation feature

[mattallan]

WooCommerce 9.3 shipped on September 13th which has deprecated the Navigation\Menu::add_plugin_item and Navigation\Screen::register_post_type functions with no alternative. These functions will be removed in 9.4 which is scheduled for next month.

These function are within class_exists checks so there won't be any fatals when they're removed, however we should still clean up this code.

Full deprecation notice:

[16-Sep-2024 06:05:32 UTC] Automattic\WooCommerce\Admin\Features\Navigation\Menu::add_plugin_item is deprecated since 9.3 with no alternative. Navigation classes will be removed in WooCommerce 9.4
[16-Sep-2024 06:05:32 UTC] Automattic\WooCommerce\Admin\Features\Navigation\Screen::register_post_type is deprecated since 9.3 with no alternative. Navigation classes will be removed in WooCommerce 9.4

These functions were added for Subscriptions support with the new WooCommerce navigation feature that was being worked on:

This is no longer the direction WooCommerce is going in and so they're removing all of the Navigation related code from the plugin. See: woocommerce/woocommerce#48997

To Reproduce

1. Install the latest WooCommerce version along with WooCommerce Subscriptions
2. Load any admin page
3. Open debug log to see deprecation warnings.

[mattallan]

Duplicate of #674. Closing this