Add woocommerce_attributes_saved trigger. Closes #35004.

[helgatheviking]

All Submissions:

• Have you followed the WooCommerce Contributing guideline?
• Does your code follow the WordPress' 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:

Introduce woocommerce_attributes_saved trigger in admin metabox. Explanation in #35004.

Closes #35004.

How to test the changes in this Pull Request:

Setup:

• After checking out this branch, start by recompiling legacy assets: pnpm run --filter='woocommerce/client/legacy' build.
• When you open the product editor, be sure to clear your browser's cache so that the new JS is picked up.

This change results in a new browser event being triggered: this is for the benefit of 3PDs and nothing in WooCommerce Core takes advantage of it at present, therefore there isn't really anything tangible to test. So, our first goal should simply be to confirm we have not accidentally broken anything in the product editor:

• Check you can update and then save changes to products.
• Specifically, ensure you can modify and save changes to product attributes.

Optionally, we can also perform some further tests to make sure the new event is available to 3PDs. Start by adding the following code (I suggest to a location such as wp-content/mu-plugins/test-pr-36943.php which you can remove after testing):

<?php

add_action( 'admin_footer', function () {
	echo "
		<script>
			jQuery( document.body ).on( 'woocommerce_attributes_saved', function() {
				alert( 'New event \"woocommerce_attributes_saved\" was triggered.' );
			} );
		</script>
	";
} );

With that in place:

• Refresh the product editor.
• Modify some product attributes, then click on the Save Attributes button.
• You should see an alert, as in the following screenshot.

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 created a changelog file for each project being changed, ie pnpm --filter=<project> changelog add?
• Have you included testing instructions?

FOR PR REVIEWER ONLY:

• I have reviewed that everything is sanitized/escaped appropriately for any SQL or XSS injection possibilities. I made sure Linting is not ignored or disabled.

[codecov]

Codecov Report

Merging #36943 (c8074a7) into trunk (f9f6e68) will increase coverage by 0.0%.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff            @@
##             trunk   #36943   +/-   ##
========================================
  Coverage     46.7%    46.7%           
  Complexity   17178    17178           
========================================
  Files          429      429           
  Lines        64779    64779           
========================================
+ Hits         30240    30242    +2     
+ Misses       34539    34537    -2     

Impacted Files	Coverage Δ
plugins/woocommerce/includes/class-wc-tax.php	79.0% <0.0%> (+0.5%)	⬆️

[barryhughes]

Looks good, thank you!

• Changelog added.
• Further testing instructions added.