[Core] Move ray_utils.py from engine to executor package (#4347)

vllm/engine/llm_engine.py

@@ -15,8 +15,8 @@ from vllm.engine.output_processor.interfaces import (
     SequenceGroupOutputProcessor)
 from vllm.engine.output_processor.stop_checker import StopChecker
 from vllm.engine.output_processor.util import create_output_by_sequence_group
-from vllm.engine.ray_utils import initialize_ray_cluster
 from vllm.executor.executor_base import ExecutorBase
+from vllm.executor.ray_utils import initialize_ray_cluster
 from vllm.logger import init_logger
 from vllm.lora.request import LoRARequest
 from vllm.outputs import RequestOutput