### 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
CLUSTER_ID = 'cluster_id'
RUN_ID = 1
JOB_ID = 42
HOST = 'xx.cloud.databricks.com'
HOST_WITH_SCHEME = 'https://xx.cloud.databricks.com'
LOGIN = 'login'
PASSWORD = 'password'
TOKEN = 'token'
USER_AGENT_HEADER = {'user-agent': f'airflow-{__version__}'}
RUN_PAGE_URL = 'https://XX.cloud.databricks.com/#jobs/1/runs/1'
LIFE_CYCLE_STATE = 'PENDING'
STATE_MESSAGE = 'Waiting for cluster'
GET_RUN_RESPONSE = {
    'job_id': JOB_ID,
    'run_page_url': RUN_PAGE_URL,
    'state': {'life_cycle_state': LIFE_CYCLE_STATE, 'state_message': STATE_MESSAGE},
}
NOTEBOOK_PARAMS = {"dry-run": "true", "oldest-time-to-consider": "1457570074236"}
JAR_PARAMS = ["param1", "param2"]
RESULT_STATE = None  
LIBRARIES = [
    {"jar": "dbfs:/mnt/libraries/library.jar"},
    {"maven": {"coordinates": "org.jsoup:jsoup:1.7.2", "exclusions": ["slf4j:slf4j"]}},
]
def run_now_endpoint(host):
    """
    Utility function to generate the run now endpoint given the host.
    """
    return f'https://{host}/api/2.1/jobs/run-now'
def submit_run_endpoint(host):