Remove Woo Navigation integration

[ibndawood]

The new Woo Navigation feature will be removed from the core. All related code should be removed. We should basically revert this PR: #1802

Here are the methods that are deprecated in 9.3 and shall be removed in the next version:

Warnings for /all-plugins/facebook-for-woocommerce,Facebook for WooCommerce,https://github.com/woocommerce/facebook-for-woocommerce/,3.2.7,Facebook:
method_missing,includes/Admin/Settings.php,346,"Class static method AutomatticWooCommerceAdminFeaturesNavigationMenu::add_plugin_category($args) is missing","AutomatticWooCommerceAdminFeaturesNavigationMenu::add_plugin_category($args)"
method_missing,includes/Admin/Settings.php,358,"Class static method AutomatticWooCommerceAdminFeaturesNavigationMenu::add_plugin_item($args) is missing","AutomatticWooCommerceAdminFeaturesNavigationMenu::add_plugin_item($args)"