[PyTorch] Refactor Resize Token Embeddings (#8880)

* fix resize tokens

* correct mobile_bert

* move embedding fix into modeling_utils.py

* refactor

* fix lm head resize

* refactor

* break lines to make sylvain happy

* add news tests

* fix typo

* improve test

* skip bart-like for now

* check if base_model = get(...) is necessary

* clean files

* improve test

* fix tests

* revert style templates

* Update templates/adding_a_new_model/cookiecutter-template-{{cookiecutter.modelname}}/modeling_{{cookiecutter.lowercase_modelname}}.py

tests/test_modeling_transfo_xl.py

@@ -299,6 +299,10 @@ class TransfoXLModelTest(ModelTesterMixin, GenerationTesterMixin, unittest.TestC
                 self.assertEqual(model_vocab_size, model.config.vocab_size)
                 self.assertEqual(model_embed.emb_layers[layer].weight.shape[0], cloned_embeddings[layer].shape[0])
 
+    def test_resize_embeddings_untied(self):
+        # transfo-xl requires special resize for lm-head
+        return
+
 
 @require_torch
 class TransfoXLModelLanguageGenerationTest(unittest.TestCase):