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.

with capture_templates() as templates:
        client_single_dag_edit.get("home", follow_redirects=True)
    dags = templates[0].local_context["dags"]
    assert len(dags) > 0
    dag_edit_perm_tuple = [(dag.dag_id, dag.can_edit) for dag in dags]
    assert ("filter_test_1", True) in dag_edit_perm_tuple
    assert ("filter_test_2", False) in dag_edit_perm_tuple
def test_home_robots_header_in_response(user_client):
    
    resp = user_client.get("home", follow_redirects=True)
    assert resp.headers["X-Robots-Tag"] == "noindex, nofollow"
@pytest.mark.parametrize(
    "client, flash_message, expected",
    [
        ("anonymous_client", UIAlert("hello world"), True),
        ("anonymous_client", UIAlert("hello world", roles=["Viewer"]), True),
        ("anonymous_client", UIAlert("hello world", roles=["User"]), False),
        ("anonymous_client", UIAlert("hello world", roles=["Viewer", "User"]), True),
        ("anonymous_client", UIAlert("hello world", roles=["Admin"]), False),
        ("user_client", UIAlert("hello world"), True),
        ("user_client", UIAlert("hello world", roles=["User"]), True),
        ("user_client", UIAlert("hello world", roles=["User", "Admin"]), True),
        ("user_client", UIAlert("hello world", roles=["Admin"]), False),
        ("admin_client", UIAlert("hello world"), True),
        ("admin_client", UIAlert("hello world", roles=["Admin"]), True),
        ("admin_client", UIAlert("hello world", roles=["User", "Admin"]), True),
    ],
)
def test_dashboard_flash_messages_role_filtering(request, client, flash_message, expected):