[Misc] Move utils to avoid conflicts with stdlib, and move tests (#27169)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

vllm/reasoning/abs_reasoning_parsers.py

@@ -9,7 +9,7 @@ from typing import TYPE_CHECKING, Any
 
 from vllm.entrypoints.tool_server import ToolServer
 from vllm.logger import init_logger
-from vllm.utils.collections import is_list_of
+from vllm.utils.collection_utils import is_list_of
 from vllm.utils.import_utils import import_from_path
 
 if TYPE_CHECKING: