[rollout] feat: add inter-node TRT-LLM rollout support for trtllm

[Superjomn]

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[gemini-code-assist]

Code Review

This pull request introduces unit and integration tests for multi-node and multi-replica TRT-LLM rollout scenarios, including a new test file for inter-node rollout. It also adds a bounds check in the get_pgs_and_bundle_indices method to prevent an IndexError when calculating placement group indices. I have no feedback to provide.