Add Flax BART pretraining script (#18297)
* add bart pretraining flax script
* fixup
* add bart pretraining flax script
* add BART to README
* add BART to README
* add BART to README
* add BART to README
* add BART to README
* add bos eos document
* Update README.md
* Update README.md
* Update examples/flax/language-modeling/run_bart_dlm_flax.py
Co-authored-by: Sanchit Gandhi <93869735+sanchit-gandhi@users.noreply.github.com>
* final
* final
* final
* remove use_auth_token ing from_config
Co-authored-by: Sanchit Gandhi <93869735+sanchit-gandhi@users.noreply.github.com>
