WooCommerce Composite Products 10.4.0

* Fix - JS error when conditionally hiding the last component of a Composite Product configured with the 'Progressive' Layout.

* Fix - Incorrect quantity validation failure notice.
* Fix - PHP warnings when updating 'array' type properties using v2 of the WC REST API.
* Tweak - Changed default component option image size to 'woocommerce_thumbnail' for consistency with WC 3.3 image size changes (WC 3.3+ only).
* Tweak - Decoupled the 'Thumbnails' style columns count from the WooCommerce shop loop value. The default number of columns is now 3.

* Fix - Improved presentation of 'Group mode > No parent' bundles in Composite Products.
* Fix - Added support for Product Add-Ons 2.9.1.
* Fix - Some rare issues with incorrect scenario back-end validation notices and conditionally hidden components.
* Fix - Selections in hidden components incorrectly taken into account when updating the active set of scenarios, resulting in unpredictable behavior in some edge cases.
* Tweak - Retain component quantity when choosing a different Component Option.