### Body

There are some use cases where users want to trigger new DAG run as soon as one finished. This is a request I've seen several times with some variations (for example like this [Stackoverflow question](https://stackoverflow.com/q/75623153/14624409)) but the basic request is the same.

The workaround users do to get such functionality is place `TriggerDagRunOperator` as last task of their DAG invoking the same DAG:

```
from datetime import datetime

from airflow import DAG
from airflow.operators.empty import EmptyOperator
from airflow.operators.trigger_dagrun import TriggerDagRunOperator

with DAG(
    dag_id="example",
    start_date=datetime(2023, 1, 1,),
    catchup=False,
    schedule=None,
) as dag:
    task = EmptyOperator(task_id="first")
    trigger = TriggerDagRunOperator(
        task_id="trigger",
        trigger_dag_id="example",
    )

    task >> trigger

```

As you can see this works nicely:
![Screenshot 2023-03-03 at 14 20 51](https://user-images.githubusercontent.com/45845474/222718862-dfde8a41-24b6-4991-b318-b7f9784514f6.png)

My suggestion is to add first class support for this use case, so the above example will be changed to:

```

from datetime import datetime

from airflow import DAG
from airflow.operators.empty import EmptyOperator
from airflow.operators.trigger_dagrun import TriggerDagRunOperator

with DAG(
    dag_id="example",
    start_date=datetime(2023, 1, 1,),
    catchup=False,
    schedule="@continues",
) as dag:
    task = EmptyOperator(task_id="first")
```

I guess it won't exactly be `"@continues"` but more likely new [ScheduleArg](https://github.com/apache/airflow/blob/8b8552f5c4111fe0732067d7af06aa5285498a79/airflow/models/dag.py#L127) type but I show it like that just for simplification of the idea.

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
to render templates as native Python types. If False, a Jinja
        ``Environment`` is used to render templates as string values.
    :param tags: List of tags to help filtering DAGs in the UI.
    :param owner_links: Dict of owners and their links, that will be clickable on the DAGs view UI.
        Can be used as an HTTP link (for example the link to your Slack channel), or a mailto link.
        e.g: {"dag_owner": "https://airflow.apache.org/"}
    :param auto_register: Automatically register this DAG when it is used in a ``with`` block
    """
    _comps = {
        "dag_id",
        "task_ids",
        "parent_dag",
        "start_date",
        "end_date",
        "schedule_interval",
        "fileloc",
        "template_searchpath",
        "last_loaded",
    }
    __serialized_fields: frozenset[str] | None = None
    fileloc: str
    """
    File path that needs to be imported to load this DAG or subdag.
    This may not be an actual file on disk in the case when this DAG is loaded
    from a ZIP file or other DAG distribution format.
    """
    parent_dag: DAG | None = None  
    
    
    def __init__(