### Description

In Airflow UI. If we go to Browse --> DAG Runs, then DAG Runs view will be displayed.

Table contains a lot of insightful values likes DAG execution date, Start date, end date, Dag config etc

Request to add DAG duration column in the same table.
DAG Duration i.e. DAG end_date timestamp  - DAG start_date timestamp

### Use case/motivation

Analytics purpose of knowing DAG duration at all DAGs level. So that I can easily find out which DAG  have least and max duration.

### Related issues

Checked open issues. There aren't any

### 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)

airflow/www/views.py
x_points = defaultdict(list)
        cumulative_y = defaultdict(list)
        task_instances = dag.get_task_instances_before(base_date, num_runs, session=session)
        if task_instances:
            min_date = task_instances[0].execution_date
        else:
            min_date = timezone.utc_epoch()
        ti_fails = (
            session.query(TaskFail)
            .filter(
                TaskFail.dag_id == dag.dag_id,
                TaskFail.execution_date >= min_date,
                TaskFail.execution_date <= base_date,
                TaskFail.task_id.in_([t.task_id for t in dag.tasks]),
            )
            .all()
        )
        fails_totals = defaultdict(int)
        for failed_task_instance in ti_fails:
            dict_key = (
                failed_task_instance.dag_id,
                failed_task_instance.task_id,
                failed_task_instance.execution_date,
            )
            if failed_task_instance.duration:
                fails_totals[dict_key] += failed_task_instance.duration
        for task_instance in task_instances:
            if task_instance.duration:
                date_time = wwwutils.epoch(task_instance.execution_date)
                x_points[task_instance.task_id].append(date_time)