[GTIN] Add Migration support for YOAST SEO

[puntope]

Changes proposed in this Pull Request:

Closes #2665

This PR adds support for the YOAST GTIN field in the GTIN migration feature

Screenshots:

Detailed test instructions:

1. You need to have YOAST WooCommerce installed (notice the WooCommerce part, WordPress one doesn't have GTIN support)
2. Set GTIN field for a simple product in Yoast SEO Tab
3. Set GTIN field for a variation in Yoast SEO Tab (under the variations tab)
4. Start the migration using the Connection test - Start GTIN Migration (be sure there is no other AS Job already running for GTIN migration)
5. See the 2 products have the GTIN migrated
6. Delete the GTINS for those products under Product Inventory (for the simple product) and from the variations tab for the variation.
7. Start the migration using the WP CLI wp wc g4wc gtin-migration start --debug
8. See the GTIN successfully migrated
9. Run steo 7 again
10. See logs about skipping the products.

Additional details:

Changelog entry

Add - Support YOAST SEO GTIN field in the migration tools.

[codecov]

Codecov Report

Attention: Patch coverage is 14.28571% with 18 lines in your changes missing coverage. Please review.

Project coverage is 64.9%. Comparing base (b833f0c) to head (7da5ca2).
Report is 1 commits behind head on add/support-core-gtin-field.

Files with missing lines	Patch %	Lines
src/HelperTraits/GTINMigrationUtilities.php	11.1%	16 Missing ⚠️
src/Jobs/MigrateGTIN.php	0.0%	1 Missing ⚠️
src/Utility/WPCLIMigrationGTIN.php	0.0%	1 Missing ⚠️

Additional details and impacted files

@@                       Coverage Diff                       @@
##             add/support-core-gtin-field   #2677     +/-   ##
===============================================================
- Coverage                           64.9%   64.9%   -0.0%     
- Complexity                          4667    4671      +4     
===============================================================
  Files                                478     478             
  Lines                              19517   19527     +10     
===============================================================
  Hits                               12674   12674             
- Misses                              6843    6853     +10     

Flag	Coverage Δ
php-unit-tests	64.9% <14.3%> (-<0.1%)	⬇️

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

Files with missing lines	Coverage Δ
src/Integration/YoastWooCommerceSeo.php	81.2% <100.0%> (ø)
src/Jobs/MigrateGTIN.php	0.0% <0.0%> (ø)
src/Utility/WPCLIMigrationGTIN.php	0.0% <0.0%> (ø)
src/HelperTraits/GTINMigrationUtilities.php	21.6% <11.1%> (-8.0%)	⬇️

[mikkamp]

Thanks for providing the compatibility. I tested it and it does work as expected, however I think it would be nicer to keep the integration functionality encapsulated in the one class.

[mikkamp]

This structure does work, but it wouldn't be my preferred choice, as it requires the migration to know details about Yoast compatibility as well as having access to public methods.

While we only added support for Yoast in theory there could be other plugins which add support for their structure. Which is why each class in the Integrations folder was implemented in such a way that in theory it could live both in the plugin and outside the plugin (maintained by a 3PD).

I think it would be better to keep it that way and add any necessary hooks so we don't need to make parts of the Yoast integration classes public.

[mikkamp]

So just add a filter in get_gtin so we don't need to add anything in regards to Yoast here. Then in the class YoastWooCommerceSeo we can hook into the filter for migration and if it has a value to return it can do so.