### 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)

airflow/providers/databricks/hooks/databricks.py
#
#
#
"""
Databricks hook.
This hook enable the submitting and running of jobs to the Databricks platform. Internally the
operators talk to the ``api/2.0/jobs/runs/submit``
`endpoint <https://docs.databricks.com/api/latest/jobs.html#runs-submit>`_.
"""
import time
from time import sleep
from urllib.parse import urlparse
import requests
from requests import PreparedRequest, exceptions as requests_exceptions
from requests.auth import AuthBase
from airflow import __version__
from airflow.exceptions import AirflowException
from airflow.hooks.base import BaseHook
RESTART_CLUSTER_ENDPOINT = ("POST", "api/2.0/clusters/restart")
START_CLUSTER_ENDPOINT = ("POST", "api/2.0/clusters/start")
TERMINATE_CLUSTER_ENDPOINT = ("POST", "api/2.0/clusters/delete")
RUN_NOW_ENDPOINT = ('POST', 'api/2.1/jobs/run-now')
SUBMIT_RUN_ENDPOINT = ('POST', 'api/2.1/jobs/runs/submit')
GET_RUN_ENDPOINT = ('GET', 'api/2.1/jobs/runs/get')
CANCEL_RUN_ENDPOINT = ('POST', 'api/2.1/jobs/runs/cancel')
INSTALL_LIBS_ENDPOINT = ('POST', 'api/2.0/libraries/install')
UNINSTALL_LIBS_ENDPOINT = ('POST', 'api/2.0/libraries/uninstall')
USER_AGENT_HEADER = {'user-agent': f'airflow-{__version__}'}