Add OpenChat, Alpaca, Vicuna chat templates (#6397)

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