Everything related to the ``__implements__`` construct was removed. It was based on PEP245
that was proposed in 2001 and rejected in 2006.

All the classes inheriting ``Interface`` in ``pylint.interfaces`` were removed.
``Checker`` should only inherit ``BaseChecker`` or any of the other checker types
from ``pylint.checkers``. ``Reporter`` should only inherit ``BaseReporter``.

Refs #8404