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.

"""
        An endpoint helping check the health status of the Airflow instance,
        including metadatabase and scheduler.
        """
        payload = {"metadatabase": {"status": "unhealthy"}}
        latest_scheduler_heartbeat = None
        scheduler_status = "unhealthy"
        payload["metadatabase"] = {"status": "healthy"}
        try:
            scheduler_job = SchedulerJobRunner.most_recent_job()
            if scheduler_job:
                latest_scheduler_heartbeat = scheduler_job.latest_heartbeat.isoformat()
                if scheduler_job.is_alive():
                    scheduler_status = "healthy"
        except Exception:
            payload["metadatabase"]["status"] = "unhealthy"
        payload["scheduler"] = {
            "status": scheduler_status,
            "latest_scheduler_heartbeat": latest_scheduler_heartbeat,
        }
        return flask.json.jsonify(payload)
    @expose("/home")
    @auth.has_access(
        [
            (permissions.ACTION_CAN_READ, permissions.RESOURCE_WEBSITE),
        ]
    )
    def index(self):