[Frontend] Add Command-R and Llama-3 chat template

[ccs96307]

This PR adds several chat templates in Jinja format.

The added templates are:

• examples/rag_chat_template_command_r.jinja
• examples/template_command_r.jinja
• examples/template_llama3.jinja
• examples/tool_chat_template_command_r.jinja

I noticed there are a feature request issue #9904 about adding chat template and I think I can help (I am researching how to use jinja to format my chat history processing recently). I have always wanted to contribute to the vLLM project, and I hope this PR can be a meaningful addition.

If the maintainers think these templates are unnecessary or beyond the project's scope, I am open to feedback and will happily adjust or close the PR as needed.

FIX #9904

Added: My Command-R chat template is based on CohereForAI/c4ai-command-r-08-2024

[github-actions]

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[DarkLight1337]

cc @K-Mistele

[K-Mistele]

One final note, might be good to have the chat templates for command-r named consistently, e.g. command_r_tool_chat_template, command_r_rag_chat_template, comand_r_default_chat_template or something.

[K-Mistele]

I don't understand why this is necessary. Llama 3's chat template is already included in the model's tokenizer_config.json and this omits functionality like tool calls. What is the use case for this?

[ccs96307]

Sure, I'll standardize the template names. Honestly, in terms of usefulness, Llama-3 isn't something I particularly care about—it's just that it was mentioned in the issue, so I tried adding it.

Should I remove it?

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @ccs96307.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[ccs96307]

Hi @K-Mistele , just following up on this PR. Please let me know if any further changes are needed or if there's anything else I can do to help. Thanks!