The DAGs main page has All/Active/Paused.

It would be nice if we can have also Running Now which will show all the DAGs that have at least 1 in Running of DAG runs:
![Screen Shot 2021-08-25 at 11 30 55](https://user-images.githubusercontent.com/62940116/130756490-647dc664-7528-4eb7-b4d8-515577f7e6bb.png)


For the above example the new DAGs tab of Running Now should show only 2 rows.
The use case is to see easily what DAGs are currently in progress.

"""Clears the state."""
        try:
            count = 0
            cleared_ti_count = 0
            dag_to_tis: dict[DAG, list[TaskInstance]] = {}
            for dr in session.query(DagRun).filter(DagRun.id.in_([dagrun.id for dagrun in drs])).all():
                count += 1
                dag = get_airflow_app().dag_bag.get_dag(dr.dag_id)
                tis_to_clear = dag_to_tis.setdefault(dag, [])
                tis_to_clear += dr.get_task_instances()
            for dag, tis in dag_to_tis.items():
                cleared_ti_count += len(tis)
                models.clear_task_instances(tis, session, dag=dag)
            flash(f"{count} dag runs and {cleared_ti_count} task instances were cleared")
        except Exception:
            flash("Failed to clear state", "error")
        return redirect(self.get_default_url())
class LogModelView(AirflowModelView):
    """View to show records from Log table."""
    route_base = "/log"
    datamodel = AirflowModelView.CustomSQLAInterface(Log)  
    class_permission_name = permissions.RESOURCE_AUDIT_LOG