Big file_utils cleanup (#16396)

* Big file_utils cleanup

* This one still needs to be treated separately

templates/adding_a_new_model/open_model_proposals/ADD_BIG_BIRD.md

@@ -532,7 +532,7 @@ to make your debugging environment as efficient as possible.
     due to multiple dropout layers in the model. Make sure that the
     forward pass in your debugging environment is **deterministic** so
     that the dropout layers are not used. Or use
-    `transformers.file_utils.set_seed` if the old and new
+    `transformers.utils.set_seed` if the old and new
     implementations are in the same framework.
 
 #### (Important) More details on how to create a debugging environment for BigBird 

utils/tests_fetcher.py

@@ -268,6 +268,8 @@ SPECIAL_MODULE_TO_TEST_MAP = {
     "feature_extraction_sequence_utils.py": "test_sequence_feature_extraction_common.py",
     "feature_extraction_utils.py": "test_feature_extraction_common.py",
     "file_utils.py": ["utils/test_file_utils.py", "utils/test_model_output.py"],
+    "utils/generic.py": ["utils/test_file_utils.py", "utils/test_model_output.py"],
+    "utils/hub.py": "utils/test_file_utils.py",
     "modelcard.py": "utils/test_model_card.py",
     "modeling_flax_utils.py": "test_modeling_flax_common.py",
     "modeling_tf_utils.py": ["test_modeling_tf_common.py", "utils/test_modeling_tf_core.py"],