[router] LSH based prefix cache aware router

### 🚀 Feature Description and Motivation

Right now, we're using xxhash in https://github.com/aibrix/aibrix/pull/641 for our prefix cache-aware router. We might consider switching to a consistent hash + LSH-based approach, which could reduce accuracy a bit but would simplify scaling. Here are some related discussions: https://github.com/vllm-project/production-stack/issues/59#issuecomment-2656740442.

### Use Case

N/A

### Proposed Solution

_No response_