Convert Purge plugins to attributes

Problem/Motivation

As per https://www.drupal.org/node/3395582 not providing an attribute class is deprecated in 11.2

If we raise the minimum supported version to 10.2 then we can safely remove the annotations.

Steps to reproduce

N/A

Proposed resolution

• Add 7 new PHP 8 attribute classes in src/Attribute/ (one for each plugin type)
• Update all 7 plugin managers to support both attributes and annotations for backward compatibility
• Convert all core and test module plugins from annotations to attributes
• Preserve existing annotation classes in src/Annotation/ so contrib modules can migrate at their own pace

Remaining tasks

Do it

User interface changes

N/A

API changes

Annotations removed, attributes added.

Data model changes

N/A