### 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
#
#
#
#
import itertools
import json
import unittest
from unittest import mock
import pytest
from requests import exceptions as requests_exceptions
from airflow import __version__
from airflow.exceptions import AirflowException
from airflow.models import Connection
from airflow.providers.databricks.hooks.databricks import (
    AZURE_DEFAULT_AD_ENDPOINT,
    AZURE_MANAGEMENT_ENDPOINT,
    AZURE_TOKEN_SERVICE_URL,
    DEFAULT_DATABRICKS_SCOPE,
    SUBMIT_RUN_ENDPOINT,
    DatabricksHook,
    RunState,
)
from airflow.utils.session import provide_session
TASK_ID = 'databricks-operator'
DEFAULT_CONN_ID = 'databricks_default'
NOTEBOOK_TASK = {'notebook_path': '/test'}
SPARK_PYTHON_TASK = {'python_file': 'test.py', 'parameters': ['--param', '123']}
NEW_CLUSTER = {'spark_version': '2.0.x-scala2.10', 'node_type_id': 'r3.xlarge', 'num_workers': 1}