### Apache Airflow Provider(s)

databricks

### Versions of Apache Airflow Providers

apache-airflow-providers-databricks==1!2.0.2


### Apache Airflow version

2.1.4 (latest released)

### Operating System

Debian GNU/Linux 11 (bullseye)

### Deployment

Docker-Compose

### Deployment details

Running local deployment using Astronomer CLI

### What happened

When calling the `get_run_state` method from the `DatabricksHook`, I get the following error:

`TypeError: Object of type RunState is not JSON serializable`

I think this is due to [the method returning a RunState custom class](https://github.com/apache/airflow/blob/main/airflow/providers/databricks/hooks/databricks.py#L275) as opposed to a `str` like the rest of the methods in the databricks hook (i.e. `get_job_id`, `get_run_page_url`, etc.)

### What you expected to happen

When calling the `get_run_state` method, simply return the `result_state` or `state_message` [variables](https://github.com/apache/airflow/blob/main/airflow/providers/databricks/hooks/databricks.py#L287-L288) instead of the `RunState` class.

### How to reproduce

Create a dag that references a databricks deployment and use this task to see the error:

```
    from airflow.providers.databricks.hooks.databricks import DatabricksHook
    run_id = <insert run id from databricks ui here>

    def get_run_state(self, run_id: str):
           return self.hook.get_run_state(run_id=run_id)

    python_get_run_state = PythonOperator(
        task_id="python_get_run_state",
        python_callable=get_run_state,
        op_kwargs={
            "run_id": str(run_id)
        }
    )
```

### Anything else

_No response_

### Are you willing to submit PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

tests/providers/databricks/hooks/test_databricks.py
"""
    Tests for DatabricksHook when auth is done with AAD token for SP outside of workspace.
    """
    @provide_session
    def setUp(self, session=None):
        conn = session.query(Connection).filter(Connection.conn_id == DEFAULT_CONN_ID).first()
        self.tenant_id = '3ff810a6-5504-4ab8-85cb-cd0e6f879c1d'
        self.client_id = '9ff815a6-4404-4ab8-85cb-cd0e6f879c1d'
        conn.login = self.client_id
        conn.password = 'secret'
        conn.host = HOST
        conn.extra = json.dumps(
            {
                'azure_resource_id': '/Some/resource',
                'azure_tenant_id': '3ff810a6-5504-4ab8-85cb-cd0e6f879c1d',
            }
        )
        session.commit()
        self.hook = DatabricksHook()
    @mock.patch('airflow.providers.databricks.hooks.databricks.requests')
    def test_submit_run(self, mock_requests):