refactor(workflow-file): move core.file to core.workflow.file (#32252)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

api/core/agent/base_agent_runner.py

@@ -17,7 +17,6 @@ from core.app.entities.app_invoke_entities import (
 )
 from core.callback_handler.agent_tool_callback_handler import DifyAgentCallbackHandler
 from core.callback_handler.index_tool_callback_handler import DatasetIndexToolCallbackHandler
-from core.file import file_manager
 from core.memory.token_buffer_memory import TokenBufferMemory
 from core.model_manager import ModelInstance
 from core.model_runtime.entities import (
@@ -40,6 +39,7 @@ from core.tools.entities.tool_entities import (
 )
 from core.tools.tool_manager import ToolManager
 from core.tools.utils.dataset_retriever_tool import DatasetRetrieverTool
+from core.workflow.file import file_manager
 from extensions.ext_database import db
 from factories import file_factory
 from models.enums import CreatorUserRole