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 self._set_notification_property(items, "email_sent", True)
    @action(
        "mulemailsentfalse",
        "Set email sent to false",
        "Are you sure you want to mark these SLA alerts as emails not sent yet?",
        single=False,
    )
    def action_mulemailsentfalse(self, items: list[SlaMiss]):
        return self._set_notification_property(items, "email_sent", False)
    @provide_session
    def _set_notification_property(
        self,
        items: list[SlaMiss],
        attr: str,
        new_value: bool,
        session: Session = NEW_SESSION,
    ):
        try:
            count = 0
            for sla in items:
                count += 1
                setattr(sla, attr, new_value)
                session.merge(sla)
            session.commit()
            flash(f"{count} SLAMisses had {attr} set to {new_value}.")
        except Exception as ex:
            flash(str(ex), "error")
            flash("Failed to set state", "error")
        self.update_redirect()
        return redirect(self.get_default_url())