BookingWP - WooCommerce Appointments 4.22.1

* Improvement - Removed code for very old WooCommerce versions not supported any more.
* Fix - Payments can remain unpaid when payment gateways complete orders early.

* Improvement - Prioritize WC_Customer data over pulling customer info from orders.
* Improvement - Updated French translation.
* Improvement - Cached WC_Order and WC_Customer queries for the appointment object.
* Improvement - Better code standards (phase 1).
* Improvement - Updated Product Add-ons to 3.5.0.
* Fix - Flush cache for products with single staff.
* Fix - Don't cancel already cancelled appointment during sync.
* Fix - Recurring events can sync with 1 hour difference (DST issue).

* Improvement - Add 'woocommerce_appointments_gcal_sync_order_meta' filter for order meta sync.
* Fix - Make compatibility check for navigation work correctly in older WC versions.
* Fix - Updating appointment changes from the synced gcal event can break time.
* Fix - Sync appointment changes to the calendar event's description.