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 admin_client:
        admin_client.get("home", follow_redirects=True)
        assert "all" == flask.session[FILTER_STATUS_COOKIE]
        admin_client.get("home?status=active", follow_redirects=True)
        assert "active" == flask.session[FILTER_STATUS_COOKIE]
        admin_client.get("home?status=paused", follow_redirects=True)
        assert "paused" == flask.session[FILTER_STATUS_COOKIE]
        admin_client.get("home?status=all", follow_redirects=True)
        assert "all" == flask.session[FILTER_STATUS_COOKIE]
@pytest.fixture(scope="module")
def user_single_dag(app):
    """Create User that can only access the first DAG from TEST_FILTER_DAG_IDS"""
    return create_user(
        app,
        username="user_single_dag",
        role_name="role_single_dag",
        permissions=[
            (permissions.ACTION_CAN_READ, permissions.RESOURCE_WEBSITE),
            (permissions.ACTION_CAN_READ, permissions.resource_name_for_dag(TEST_FILTER_DAG_IDS[0])),
        ],
    )
@pytest.fixture()
def client_single_dag(app, user_single_dag):