[Feature] Add LlamaCPP as server engine option

llama.cpp is exposing OpenAI compatible APIs and works perfectly fine
with genai-bench.

Author: rgerganov

genai_bench/cli/option_groups.py

@@ -357,7 +357,7 @@ def server_options(func):
     func = click.option(
         "--server-engine",
         type=click.Choice(
-            ["vLLM", "SGLang", "TGI", "cohere-TensorRT", "cohere-vLLM"],
+            ["vLLM", "SGLang", "TGI", "cohere-TensorRT", "cohere-vLLM", "LlamaCPP"],
             case_sensitive=True,
         ),
         required=False,