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 mock.patch("airflow.settings.DASHBOARD_UIALERTS", [flash_message]):
        resp = request.getfixturevalue(client).get("home", follow_redirects=True)
    if expected:
        check_content_in_response(flash_message.message, resp)
    else:
        check_content_not_in_response(flash_message.message, resp)
def test_dashboard_flash_messages_many(user_client):
    messages = [
        UIAlert("hello world"),
        UIAlert("im_not_here", roles=["Admin"]),
        UIAlert("_hello_world_"),
    ]
    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_not_in_response("im_not_here", resp)
    check_content_in_response("_hello_world_", resp)
def test_dashboard_flash_messages_markup(user_client):
    link = '<a href="http://example.com">hello world</a>'
    user_input = markupsafe.Markup("Hello <em>%s</em>") % ("foo&bar",)
    messages = [
        UIAlert(link, html=True),
        UIAlert(user_input),
    ]
    with mock.patch("airflow.settings.DASHBOARD_UIALERTS", messages):
        resp = user_client.get("home", follow_redirects=True)
    check_content_in_response(link, resp)
    check_content_in_response(user_input, resp)
def test_dashboard_flash_messages_type(user_client):