Add TensorRT-LLM support as another backend

[kerthcet]

What would you like to be added:

Add support for https://github.com/NVIDIA/TensorRT-LLM?tab=readme-ov-file

see blog like https://developer.nvidia.com/blog/optimizing-inference-on-llms-with-tensorrt-llm-now-publicly-available/

Why is this needed:

Completion requirements:

This enhancement requires the following artifacts:

• Design doc
• API change
• Docs update

The artifacts should be linked in subsequent comments.