Support for GenEval

[yansenhan]

We really appreciate for this great work. However, it currently only support Pickscore and OCR. In FlowGRPO and DiffusionNFT, we find they include GenEval metric and want know there is any plan for supporting GenEval.

[Jayce-Ping]

The dependencies for GenEval are currently incompatible with (or too outdated for) this repository. I suggest following the approach used in FlowGRPO: implementing GenEval as a separate reward server. You can then interface with it using the provided RemoteRewardModel to keep the environments decoupled.