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.

"""Set state to success."""
        try:
            count = 0
            altered_tis = []
            for dr in session.query(DagRun).filter(DagRun.id.in_([dagrun.id for dagrun in drs])).all():
                count += 1
                altered_tis += set_dag_run_state_to_success(
                    dag=get_airflow_app().dag_bag.get_dag(dr.dag_id),
                    run_id=dr.run_id,
                    commit=True,
                    session=session,
                )
            altered_ti_count = len(altered_tis)
            flash(f"{count} dag runs and {altered_ti_count} task instances were set to success")
        except Exception:
            flash("Failed to set state", "error")
        return redirect(self.get_default_url())
    @action("clear", "Clear the state", "All task instances would be cleared, are you sure?", single=False)
    @action_has_dag_edit_access
    @provide_session
    @action_logging
    def action_clear(self, drs: list[DagRun], session: Session = NEW_SESSION):