Add OpenChat, Alpaca, Vicuna chat templates (#6397)
* Add openchat chat template
* Add chat template test for openchat
* Add chat template for vicuna
* Add chat template for orca-vicuna
* Add EOS for vicuna templates
* Combine vicuna chat templates
* Add tests for openchat and vicuna chat templates
* Add chat template for alpaca
* Add separate template name for vicuna-orca
* Remove alpaca, match deepseek with jinja output
* Regenerate chat template test with add_generation_prompt
* Separate deepseek bos from system message
* Match openchat template with jinja output
* Remove BOS token from templates, unprefix openchat
