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.

messages = [
        UIAlert("hello world", category="foo"),
    ]
    with mock.patch("airflow.settings.DASHBOARD_UIALERTS", messages):
        resp = user_client.get("home", follow_redirects=True)
    check_content_in_response("hello world", resp)
    check_content_in_response("alert-foo", resp)
def test_audit_log_view(user_client, working_dags):
    resp = user_client.get("/dags/filter_test_1/audit_log")
    check_content_in_response("Dag Audit Log", resp)
@pytest.mark.parametrize(
    "url, lower_key, greater_key",
    [
        ("home?status=all", "a_first_dag_id_asc", "filter_test_1"),
        ("home?status=all&sorting_key=dag_id&sorting_direction=asc", "filter_test_1", "filter_test_2"),
        ("home?status=all&sorting_key=dag_id&sorting_direction=desc", "filter_test_2", "filter_test_1"),
    ],
    ids=["no_order_provided", "ascending_order_on_dag_id", "descending_order_on_dag_id"],
)
def test_sorting_home_view(url, lower_key, greater_key, user_client, working_dags):
    resp = user_client.get(url, follow_redirects=True)
    resp_html = resp.data.decode("utf-8")
    lower_index = resp_html.find(lower_key)
    greater_index = resp_html.find(greater_key)
    assert lower_index < greater_index