### Description

Add listeners for Datasets (events)

### Use case/motivation

As Airflow administrators, we would like to trigger some external processes based on all datasets being created/updated by our users. We came across the listeners for the dag runs and task instances (which are also useful), but are still missing listeners for datasets.

### 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)

warnings.warn(
            "`DAG.is_fixed_time_schedule()` is deprecated.",
            category=RemovedInAirflow3Warning,
            stacklevel=2,
        )
        try:
            return not self.timetable._should_fix_dst
        except AttributeError:
            return True
    def following_schedule(self, dttm):
        """
        Calculate the following schedule for this dag in UTC.
        :param dttm: utc datetime
        :return: utc datetime
        """
        warnings.warn(
            "`DAG.following_schedule()` is deprecated. Use `DAG.next_dagrun_info(restricted=False)` instead.",
            category=RemovedInAirflow3Warning,
            stacklevel=2,
        )
        data_interval = self.infer_automated_data_interval(timezone.coerce_datetime(dttm))
        next_info = self.next_dagrun_info(data_interval, restricted=False)
        if next_info is None:
            return None
        return next_info.data_interval.start
    def previous_schedule(self, dttm):