[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
