pylint: updates related to deprecations
    
    pylint 3.0 has deprectated a few functions:
    - check_messages: Use utils.only_required_for_messages
    - The config attribute of BaseChecker has been deprecated. You can
    use checker.linter.config to access the global configuration object
    instead of a checker-specific object
    - Everything related to the __implements__ construct was removed.
    - Checker should only inherit BaseChecker or any of the other checker
    types from pylint.checkers.
    
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>