fix(autocomplete-orders): apply option to variations, not parent product

[dkoo]

When the product being checked is a variation, check the newspack_autocomplete_orders meta value for the parent item, not the variation.

All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

#3072 added a custom product option to allow autocompletion of orders with that product. #3111 restricted this option to usage with "virtual" products, while #3692 rescinded that requirement based on publisher feedback, but didn't remove the wrapper classes that hid the option from non-virtual products and variations, creating confusion and making it impossible to properly set the option value on non-virtual products.

This PR clarifies the usage of the option by adding a new product_types config key to custom options, so that the options will only be shown and filters applied for products that match the supported types.

How to test the changes in this Pull Request:

1. Check out this branch and pubilsh four products:

• A simple product, non-virtual
• A variable product, non-virtual, with variations
• A simple subscription, virtual
• A variable subscription, virtual, with variations

2. For each of the four products, ensure that the "Auto-complete orders" checkbox option appears at the top of the "Product data" box for simple products and simple subscription products, while for variable products it appears only inside each variation and not at the top-level parent product's product data box. Leave the option checked for all products and variations.

3. As a reader, purchase all products/variations. In the admin, confirm that all orders are created with the "Completed" status.
4. Uncheck the "Auto-complete orders" option for all products and variations and save.
5. As a reader, repurchase all products/variations, and this time confirm that all orders are creating with the "Processing" status.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

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[adekbadek]

Works as descibed 👌

[matticbot]

🎉 This PR is included in version 6.6.4 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀