Move the benchmark codes to aibrix python package

[Jeffwan]

🚀 Feature Description and Motivation

We can consider to make code reusable and move to https://github.com/vllm-project/aibrix/tree/main/python/aibrix

This make the generator/benchmark code reusable.

Use Case

As a user, I want a single benchmark scripts to help me cover the inference engine testing

Proposed Solution

No response