docs: Add example how to enable Ray on GKE cluster

[MaksYermak]

In this PR I have prepared DAG for showing how to enable Ray on GKE cluster

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[eladkal]

Tests are failing:

FAILED airflow-core/tests/unit/always/test_example_dags.py::test_should_be_importable[providers/google/tests/system/google/cloud/kubernetes_engine/example_kubernetes_engine_ray.py] - AssertionError: import_errors={'/opt/airflow/providers/google/tests/system/google/cloud/kubernetes_engine/example_kubernetes_engine_ray.py': 'Traceback (most recent call last):\n  File "/opt/airflow/task-sdk/src/airflow/sdk/bases/operator.py", line 502, in apply_defaults\n    result = func(self, **kwargs, default_args=default_args)\n  File "/opt/airflow/task-sdk/src/airflow/sdk/bases/operator.py", line 1026, in __init__\n    raise TypeError(\nTypeError: Invalid arguments were passed to GKEDeleteClusterOperator (task_id: delete_cluster). Invalid arguments were:\n**kwargs: {\'name\': \'cluster-kubernetes-engine-ray-\'}\n'}
assert 1 == 0
 +  where 1 = len({'/opt/airflow/providers/google/tests/system/google/cloud/kubernetes_engine/example_kubernetes_engine_ray.py': 'Traceb...erator (task_id: delete_cluster). Invalid arguments were:\n**kwargs: {\'name\': \'cluster-kubernetes-engine-ray-\'}\n'})
 +    where {'/opt/airflow/providers/google/tests/system/google/cloud/kubernetes_engine/example_kubernetes_engine_ray.py': 'Traceb...erator (task_id: delete_cluster). Invalid arguments were:\n**kwargs: {\'name\': \'cluster-kubernetes-engine-ray-\'}\n'} = <airflow.models.dagbag.DagBag object at 0x7fa1eecf72b0>.import_errors

[MaksYermak]

Tests are failing:

FAILED airflow-core/tests/unit/always/test_example_dags.py::test_should_be_importable[providers/google/tests/system/google/cloud/kubernetes_engine/example_kubernetes_engine_ray.py] - AssertionError: import_errors={'/opt/airflow/providers/google/tests/system/google/cloud/kubernetes_engine/example_kubernetes_engine_ray.py': 'Traceback (most recent call last):\n  File "/opt/airflow/task-sdk/src/airflow/sdk/bases/operator.py", line 502, in apply_defaults\n    result = func(self, **kwargs, default_args=default_args)\n  File "/opt/airflow/task-sdk/src/airflow/sdk/bases/operator.py", line 1026, in __init__\n    raise TypeError(\nTypeError: Invalid arguments were passed to GKEDeleteClusterOperator (task_id: delete_cluster). Invalid arguments were:\n**kwargs: {\'name\': \'cluster-kubernetes-engine-ray-\'}\n'}
assert 1 == 0
 +  where 1 = len({'/opt/airflow/providers/google/tests/system/google/cloud/kubernetes_engine/example_kubernetes_engine_ray.py': 'Traceb...erator (task_id: delete_cluster). Invalid arguments were:\n**kwargs: {\'name\': \'cluster-kubernetes-engine-ray-\'}\n'})
 +    where {'/opt/airflow/providers/google/tests/system/google/cloud/kubernetes_engine/example_kubernetes_engine_ray.py': 'Traceb...erator (task_id: delete_cluster). Invalid arguments were:\n**kwargs: {\'name\': \'cluster-kubernetes-engine-ray-\'}\n'} = <airflow.models.dagbag.DagBag object at 0x7fa1eecf72b0>.import_errors

@eladkal I have fixed the problem