Add web worker offloading plugin

[thelovekesh]

Summary

Fixes #176

Previously: #556

Relevant technical choices

• Add Web Worker Offloading standalone plugin which allows running scripts within the worker thread with the help of the Partytown library.
• Add the wwo_configuration filter which can be used to update web worker configurations.

Testing steps

• Enable this performance plugin or use wp-env in which this plugin is enabled by default on this branch.

• Add a JS script with web-worker-offloading as a dependency. When the page is loaded, the JS script should be loaded within the web worker.

  function enqueue_non_critical_js() {
      wp_enqueue_script(
    	  'non-critical-js',
    	  '/path/to/non-critical.js',
    	  array( 'web-worker-offloading' ), // Note the `web-worker-offloading` being added as a dep
    	  '1.0.0',
    	  true
      );
  }
  add_action( 'wp_enqueue_scripts', 'enqueue_non_critical_js' );

• Use wwo_configuration hook to update web worker configurations.

  function update_wwo_config( $config ) {
    $config["debug"] = true;
    return $config;
  }
  add_filter( 'wwo_configuration', 'update_wwo_config' );

[thelovekesh]

@westonruter @adamsilverstein I have converted this into a standalone plugin. Next, I'll add a settings page to opt-in offloading for scripts listed in the Partytown documentation (https://partytown.builder.io/common-services). This way, the WordPress plugin team won't classify it as a "framework" plugin, as @westonruter previously mentioned.

[westonruter]

Just some trivial suggestions left from me. Pre-approving so that once @adamsilverstein approves this can finally be merged!

[adamsilverstein]

Nice!

[adamsilverstein]

Code looks good to me, doing some manual testing next.

[adamsilverstein]

Testing this locally with the sample code from the ticket description, I noticed the script handle is different, I had to use
'web-worker-offloading' while the instructions for testing in the description use 'web-worker-offloader'. Can you update that in the testing instructions for posterity?

Once I did that, the tag got the partytown type added:

question: do we want to remove the data-wp-strategy attribute as well?

I didn't test actual Partytown functionality yet, that will be easier to do once we ship the plugin. Are we planning add script specific handling (eg analytics) in the future?

[adamsilverstein]

Tremendous!

[westonruter]

Testing this locally with the sample code from the ticket description, I noticed the script handle is different, I had to use
'web-worker-offloading' while the instructions for testing in the description use 'web-worker-offloader'. Can you update that in the testing instructions for posterity?

Ah, that's my bad. I updated the slug in the codebase but didn't do it in the description. Updated now.

question: do we want to remove the data-wp-strategy attribute as well?

You're right. This can be removed as well. Or the async attribute can be left as-is. I think it may make sense to keep async since this in effect what offloading to Partytown results in. (Or maybe defer actually. I'm not entirely sure of the execution model.) But ultimately, on second thought, let's remove it because if the user didn't add async to begin with, it could be confusing why it is showing up.

[westonruter]

In 44c469c I addressed a case where a script may already have the defer or async strategy and then its opted-into offloading to web worker. I've added the plugin banner and icon asset.

✅ Good to merge.

[westonruter]

Follow up: #1468