Improved - Switched from wc-ajax=update_checkout to wc-ajax=update_order_review - this aligns our AJAX refresh with core's and handles edge cases where plugins look at the URL to determine the type of request happening (generally an anti-pattern). It also works properly when CheckoutWC is bypassed or disabled.
Fix - Smarty address validation now works with the One Page Checkout option
Fix - Fix issue where temporary alerts weren't cleared on subsequent AJAX refreshes unless there were new alerts to show.
Dev - Added messages to the update_order_review response package because it's in Woo core and some plugins like to use it
Dev - Fixed HPOS incompatibilities in our stat collection class.
