Product Block Editor: Make it compatible with WooCommerce 8.6

[eason9487]

Changes proposed in this Pull Request:

In WooCommerce 8.6, the Product Block Editor has some breaking changes:

• The template of Product Block Editor is changed to be fetched via the /wc/v3/layout-templates REST API.
  • Ref: Remove BlockTemplateRegistry woocommerce#43589
• Product Block Editor starts supporting the grouped and external product types but they share the same template "simple-product".
  • Ref: Introduce a product type selection within the new experience woocommerce#41823

Before adjusting, some preprocessing makes the ProductBlocksService class easier to test:

• 355f61d: Change to use a dedicated method as the 'init' action handler.
• 175d53c: Change to use a dedicated method as the "woocommerce_block_template_area_{$template_area}_after_add_block_{$block_id}" action handler.

To be compatible with the above, it requires a few adjustments:

• f054494: Remove the is_admin_page check from the conditional registration of ProductBlocksService and set the minimum support WC version to 8.6.
• 8bbf671: Hide this extension's group from Product Block Editor for the unsupported product types.

📌 Checklist for @eason9487

• Check if all links starting with https://github.com/woocommerce/woocommerce/blob/8.6.0/[...] point to the correct lines of code.
• Revert 955a9a6 before merging

Screenshots:

Kapture.2024-02-08.at.17.22.06.mp4

Detailed test instructions:

📌 Prepare test environment

1. Please refer to the test preparation in PR 2151 with Woo 8.6.0.
   • 💡 Currently, it can be tested with 8.6.0-rc.1
2. npm install
3. npm start

📌 Test the visibility of this extension's tab and blocks

💡 By default, the supported product types of this extension are simple, variable, and variation.

1. Start creating a new product.
2. The Google Listings & Ads tab should be visible.
3. Enter product name.
4. In the General tab, change to other product types back and forth.
   
5. Check if the Google Listings & Ads tab is only visible when selecting the Standard product type.
6. Go to edit a variable product, e.g. the Hoodie imported from WC's sample products.
7. The Google Listings & Ads tab should be visible.
8. Switch to the Variations tab.
9. Click one of the Edit links within the Variations section to edit a variation product.
10. The Google Listings & Ads tab should be visible.

Changelog entry

[codecov]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (c08f614) 61.5% compared to head (ef5bdb7) 63.1%.

Additional details and impacted files

@@                           Coverage Diff                            @@
##             feature/support-product-block-editor   #2249     +/-   ##
========================================================================
+ Coverage                                    61.5%   63.1%   +1.6%     
- Complexity                                   4185    4188      +3     
========================================================================
  Files                                         748     455    -293     
  Lines                                       21538   17823   -3715     
  Branches                                      532       0    -532     
========================================================================
- Hits                                        13244   11238   -2006     
+ Misses                                       7843    6585   -1258     
+ Partials                                      451       0    -451     

Flag	Coverage Δ
js-unit-tests	?
php-unit-tests	63.1% <93.7%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/Admin/Product/ChannelVisibilityBlock.php	100.0% <ø> (ø)
src/Admin/ProductBlocksService.php	96.8% <93.7%> (ø)

... and 293 files with indirect coverage changes

[martynmjones]

Hey @eason9487, thanks for keeping this work up to date with the changes in core.

I'm seeing the Google Listings & Ads tab in the expected locations and only for the relevant product types so LGTM ✅