[Docs] Add dedicated tool calling page to docs

[mgoin]

Also adds a quickstart example for automatic function calling

[github-actions]

👋 Hi! Thank you for contributing to the vLLM project.
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[simon-mo]

@K-Mistele to review?

[mergify]

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

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