Add support for php8 Attributes

[jaapio]

https://wiki.php.net/rfc/attributes_v2

At the moment it is unsure what attributes will add to this library. But we should be able to detect the docblocks correctly. Maybe add attributes as objects on their parent:

• functions (including closures and short closures)
• classes (including anonymous classes), interfaces, traits
• class constants
• class properties
• class methods
• function/method parameters

More?