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.

return redirect(url_for("Airflow.index"))
        xcomlist = (
            session.query(XCom)
            .filter_by(dag_id=dag_id, task_id=task_id, execution_date=dttm, map_index=map_index)
            .all()
        )
        attributes = []
        for xcom in xcomlist:
            if not xcom.key.startswith("_"):
                attributes.append((xcom.key, xcom.value))
        title = "XCom"
        return self.render_template(
            "airflow/xcom.html",
            attributes=attributes,
            task_id=task_id,
            execution_date=execution_date,
            map_index=map_index,
            form=form,
            root=root,
            dag=dag,
            title=title,
        )
    @expose("/delete", methods=["POST"])
    @auth.has_access(
        [
            (permissions.ACTION_CAN_DELETE, permissions.RESOURCE_DAG),
        ]
    )
    @action_logging
    def delete(self):