Training PEFT models with new tokens being added to the embedding lay…

…ers and tokenizer (#1147)

* add support for saving base layers weights along with adapter weights

* Update save_and_load.py

* Add an example showing the usage of the added feature

* refactor the functionality

* fix

* refactoring code

1. Add `is_embedding_layer_resized` parameter to `save_pretrained`
2. Fix the deduplication in README when adding PEFT details.
3. `save_pretrained` should only save the model when `is_main_process=True` which is one of the parameters of `save_pretrained`.

* update example

* fix the model card

* fix model card

* 😅

* fix model card

* automate setting `is_embedding_layer_resized`

* nits

* Update peft_lora_clm_with_additional_tokens.ipynb

* add test

* fix tests

* maybe fixes the issue?

* address comments

Co-Authored-By: Benjamin Bossan <BenjaminBossan@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Benjamin Bossan <BenjaminBossan@users.noreply.github.com>

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Co-authored-by: Benjamin Bossan <BenjaminBossan@users.noreply.github.com>