add tensorrt_llm common and cutlass_extensions as 3rdparty

[zhyncs]

Motivation

Modifications

Checklist

• Format your code according to the Code Formatting with Pre-Commit.
• Add unit tests as outlined in the Running Unit Tests.
• Update documentation / docstrings / example tutorials as needed, according to Writing Documentation.
• Provide throughput / latency benchmark results and accuracy evaluation results as needed, according to Benchmark and Profiling.

[BBuf]

Will the common library be compiled and linked automatically?

[zhyncs]

Will the common library be compiled and linked automatically?

It's safe to merge since we haven't used any components yet. I will do this in a follow-up.

[zhyncs]

Q: Why not directly use tensorrt llm as a third_party managed by git submodule?
A: Because tensorrt llm itself is too large and has many dependencies. If used as a git submodule, installing and downloading it would either take up too much disk space or be too time-consuming.