Attribute-based ignoring of code units

[sebastianbergmann]

PHPUnit 10 introdused support for PHP 8 attributes for adding metadata to test classes and test methods as well as tested code units.

This library needs to be updated to not only ignore classes and methods based on @codeCoverageIgnore annotations in doc-comments, but also based on PHPUnit\Framework\Attributes\CodeCoverageIgnore attributes.