Reorganize file utils (#16264)

* Split file_utils in several submodules

* Fixes

* Add back more objects

* More fixes

* Who exactly decided to import that from there?

* Second suggestion to code with code review

* Revert wront move

* Fix imports

* Adapt all imports

* Adapt all imports everywhere

* Revert this import, will fix in a separate commit

tests/onnx/test_onnx_v2.py

@@ -242,7 +242,7 @@ class OnnxExportTestCaseV2(TestCase):
         onnx_config = onnx_config_class_constructor(model.config)
 
         if is_torch_available():
-            from transformers.file_utils import torch_version
+            from transformers.utils import torch_version
 
             if torch_version < onnx_config.torch_onnx_minimum_version:
                 pytest.skip(