[v5] Return a BatchEncoding dict from apply_chat_template by default (#41626)
* Flip the default return type for `apply_chat_template` to match the underlying tokenizer
* Remove test_tokenization_for_chat tests, which no longer do anything useful
* Remove test_tokenization_for_chat tests, which no longer do anything useful
* Fix test_encode_message tests
* Fix test_encode_message tests
* Return dicts for Processor too
* Fix mistral-common tests
* Catch one of the processors too
* revert test bug!
* nit fix
* nit fix