Feat: Benchmark CLI additions and documentation (#12536)

### What problem does this PR solve?

This PR adds a dedicated HTTP benchmark CLI for RAGFlow chat and
retrieval endpoints so we can measure latency/QPS.

### Type of change

- [x] Documentation Update
- [x] Other (please describe): Adds a CLI benchmarking tool for
chat/retrieval latency/QPS

---------

Co-authored-by: Liu An <asiro@qq.com>

pyproject.toml

@@ -169,6 +169,7 @@ test = [
     "reportlab>=4.4.1",
     "requests>=2.32.2",
     "requests-toolbelt>=1.0.0",
+    "pycryptodomex==3.20.0",
 ]
 
 [[tool.uv.index]]