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.

"""Multiple delete action."""
        self.datamodel.delete_all(items)
        self.update_redirect()
        return redirect(self.get_redirect())
    @action(
        "mulnotificationsent",
        "Set notification sent to true",
        "Are you sure you want to set all these notifications to sent?",
        single=False,
    )
    def action_mulnotificationsent(self, items: list[SlaMiss]):
        return self._set_notification_property(items, "notification_sent", True)
    @action(
        "mulnotificationsentfalse",
        "Set notification sent to false",
        "Are you sure you want to mark these SLA alerts as notification not sent yet?",
        single=False,
    )
    def action_mulnotificationsentfalse(self, items: list[SlaMiss]):
        return self._set_notification_property(items, "notification_sent", False)
    @action(
        "mulemailsent",
        "Set email sent to true",
        "Are you sure you want to mark these SLA alerts as emails were sent?",
        single=False,
    )
    def action_mulemailsent(self, items: list[SlaMiss]):