Reorganize repo (#8580)

* Put models in subfolders

* Styling

* Fix imports in tests

* More fixes in test imports

* Sneaky hidden imports

* Fix imports in doc files

* More sneaky imports

* Finish fixing tests

* Fix examples

* Fix path for copies

* More fixes for examples

* Fix dummy files

* More fixes for example

* More model import fixes

* Is this why you're unhappy GitHub?

* Fix imports in conver command

tests/test_tokenization_bert_japanese.py

@@ -18,14 +18,14 @@ import os
 import pickle
 import unittest
 
-from transformers.testing_utils import custom_tokenizers
-from transformers.tokenization_bert_japanese import (
+from transformers.models.bert_japanese.tokenization_bert_japanese import (
     VOCAB_FILES_NAMES,
     BertJapaneseTokenizer,
     CharacterTokenizer,
     MecabTokenizer,
     WordpieceTokenizer,
 )
+from transformers.testing_utils import custom_tokenizers
 
 from .test_tokenization_common import TokenizerTesterMixin