feat: [New Eval Benchamark] IfEval (#1708)

# What does this PR do?
In this PR, we added a new eval open benchmark IfEval based on paper
https://arxiv.org/abs/2311.07911 to measure the model capability of
instruction following.


## Test Plan
spin up a llama stack server with open-benchmark template

run `llama-stack-client --endpoint xxx eval run-benchmark
"meta-reference-ifeval" --model-id "meta-llama/Llama-3.3-70B-Instruct"
--output-dir "/home/markchen1015/" --num-examples 20` on client side and
get the eval aggregate results

.github/workflows/integration-tests.yml

@@ -52,6 +52,7 @@ jobs:
           # always test against the latest version of the client
           uv pip install git+https://github.com/meta-llama/llama-stack-client-python.git@main
           uv pip install -e .
+          llama stack build --template ollama --image-type venv
 
       - name: Wait for Ollama to start
         run: |