### 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
dr_state = dr.state
    
    if not dr_state and drs:
        dr = drs[0]
        date_time = dr.execution_date
        dr_state = dr.state
    return {
        'dttm': date_time,
        'base_date': base_date,
        'num_runs': num_runs,
        'execution_date': date_time.isoformat(),
        'dr_choices': dr_choices,
        'dr_state': dr_state,
    }
def task_group_to_tree(task_item_or_group, dag, dag_runs, tis):
    """
    Create a nested dict representation of this TaskGroup and its children used to construct
    the Graph.
    """
    if isinstance(task_item_or_group, BaseOperator):
        return {
            'id': task_item_or_group.task_id,
            'instances': [wwwutils.encode_ti(ti) for ti in tis if ti.task_id == task_item_or_group.task_id],
            'label': task_item_or_group.label,
            'extra_links': task_item_or_group.extra_links,
        }
    
    task_group = task_item_or_group
    children = [task_group_to_tree(child, dag, dag_runs, tis) for child in task_group.children.values()]
    def get_summary(dag_run, children):