[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

src/transformers/models/rag/modeling_rag.py

@@ -1459,6 +1459,9 @@ class RagTokenForGeneration(RagPreTrainedModel):
     def get_output_embeddings(self):
         return self.rag.generator.get_output_embeddings()
 
+    def set_output_embeddings(self, new_embeddings):
+        return self.rag.generator.set_output_embeddings(new_embeddings)
+
     def shift_tokens_right(self, input_ids, start_token_id=None):
         """Shift input ids one token to the right, and pad with start_token_id"""
         if start_token_id is None: