Is for showing introductions to a user, on Yoast admin pages. Based on plugin version, page, user capabilities and whether the user has seen it already.

Introduction_Interface defines what data is needed
- id as unique identifier
- plugin and version to determine if the introduction is new (version > plugin version)
- pages to be able to only show on certain Yoast admin pages
- capabilities to be able to only show for certain users
Introductions_Collector uses that data to determine whether an introduction should be "shown" to a user
- uses the wpseo_introductions filter to be extendable from our other plugins
- uses Introductions_Seen_Repository to get the data to determine if the user saw an introduction already
Introductions_Seen_Repository is the doorway whether a user has seen an introduction or not
- uses the _yoast_introductions user metadata
Introduction_Bucket and Introduction_Item are used by the collector to get an array
Introductions_Integration runs on the Yoast Admin pages and loads the assets
- only loads on our Yoast admin pages, but never on our installation success pages as to not disturb onboarding
- only loads assets if there is an introduction to show
  - js/src/introductions holds the JS
  - wpseoIntroductions is the localized script to transfer data from PHP to JS
  - css/src/ai-generator.css holds the CSS

Inside JS, register the modal content via window.YoastSEO._registerIntroductionComponent, which takes a id and a Component. The id needs to be the same as the id in the Introduction_Interface. The action yoast.introductions.ready can be used to know whether the registration function is available and ready for use.