Add support for HELM, Forbidden Questions, and AdvBench (via WildGuard proxy)

I want to add support to benchmarks like HELM and Forbidden questions, and possibly AdvBench.

I think this would give a more exhaustive list of benchmarks and would allow to better compare them.

For HELM and Forbidden questions, this is pretty straightforward; just adding the metrics and scenarios. For AdvBench, I was considering using Wildguard as a proxy.