Decorator for Task Flow (@skip_if, @run_if) to make it simple to apply whether or not to skip a Task -> Implementation also for Task Groups

### Description It would be really helpful, if the new feature @skip_if and @run_if would be available also for whole TaskGroups. With that I would be able to easily toggle the computation of whole TaskGroups with a simple check. ### Use case/motivation _No response_ ### Related issues _No response_ ### Are you willing to submit a PR? - [ ] Yes I am willing to submit a PR! ### Code of Conduct - [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)