add nvidia distribution

[cdgamarose-nv]

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What does this PR do?

adds nvidia template for creating a distribution using inference adapter for NVIDIA NIMs.

Test Plan

Please describe: Build llama stack distribution for nvidia using the template, docker and conda.

llama stack build --template nvidia

or

cd distributions/inline-nvidia/ && docker compose up

Before submitting

• [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• [ ] Ran pre-commit to handle lint / formatting issues.
• [x] Read the contributor guideline, Pull Request section?
• [x] Updated relevant documentation.
• [ ] Wrote necessary unit or integration tests.