Add EPP micro benchmark

[liu-cong]

What would you like to be added:

https://github.com/kubernetes-sigs/gateway-api-inference-extension/pull/460/files removed the outdated benchmark.go file, which wasn't using the integration framework. We should add it back but do it properly.

• Run all the reconcilers and don't inject objects to the datastore.
• Create the inference pool and model CRs for stress testing

Why is this needed:

This helps us understand performance characteristics of EPP, such as how much QPS it can handle.

[kfswain]

We seem to have other benchmarking solutions proposed, we need to converge on an agreed upon solution. I think we can hold on this for now and build some direction alignment