WooCommerce Recommendation Engine 3.4.4

* Fix: Typo in DB query for frequently purchased together.

* Update: Add view for entire session history table.
* Update: Add ability to truncate session history table to prevent issues with recommendation build timing out.
* Update: Add better visual indicators when rebuilding recommendations for specific products.
* Update: Update rebuild function to only process products which could have a potential match.
* Update: Update Maintenance to allow rebuilding specific recommendation types for performance reasons.

* Fix: Update for WC 3.x to remove notice about accessing order properties directly.
* Update: Add Woo header for automatic updates and subscriptions.