@larowlan review on #3439923

Problem/Motivation

@larowlan did a great review on #3439923: Add recipes api as experimental API to core

Proposed resolution

Do all the easy things in one issue.

List of things addressed here:

• Drop PHP 8.1 requirement - it is redundant
• References to annotations instead of attributes
• Improved docs for the config_name argument in \Drupal\Core\Config\Action\ConfigActionManager::applyAction
• Early return in \Drupal\Core\Config\Checkpoint\CheckpointStorage::checkpoint()
• Use Sequentially to avoid odd code in validateExtensionIsAvailable

Remaining tasks

User interface changes

API changes

Data model changes