Add the yaml PHP extension

[Natshah]

What in this template can be improved or added as a feature?

All Drupal 9 templates

What exactly should be updated?

Add the yaml PHP extension

How important is this feature to you?

This will promote a faster Drupal 9 site
As Drupal when importing configs with the Drupal Config Factory will use the PHP yaml functions if the extension was in the system

Issue #1920902 : Add a Drupal Yaml wrapper so we can default to PECL Yaml component if it is available

which

Additional context

No response