refactor: add AntaTest.name property

[mtache]

We should add a name property to the AntaTest abstract class instead of defining a class variable:

    @property
    def name(self) -> str:
        """Return the name of this AntaTest class."""
        return self.__class__.__name__

[gmuloc]

This has been fixed in #841. class variable was kept but it is now optional