Use inference APIs for executing Llama Guard (#121)

We should use Inference APIs to execute Llama Guard instead of directly needing to use HuggingFace modeling related code. The actual inference consideration is handled by Inference.

llama_stack/providers/utils/inference/__init__.py

@@ -3,3 +3,31 @@
 #
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
+
+from typing import List
+
+from llama_models.datatypes import *  # noqa: F403
+from llama_models.sku_list import all_registered_models
+
+
+def is_supported_safety_model(model: Model) -> bool:
+    if model.quantization_format != CheckpointQuantizationFormat.bf16:
+        return False
+
+    model_id = model.core_model_id
+    return model_id in [
+        CoreModelId.llama_guard_3_8b,
+        CoreModelId.llama_guard_3_1b,
+        CoreModelId.llama_guard_3_11b_vision,
+    ]
+
+
+def supported_inference_models() -> List[str]:
+    return [
+        m.descriptor()
+        for m in all_registered_models()
+        if (
+            m.model_family in {ModelFamily.llama3_1, ModelFamily.llama3_2}
+            or is_supported_safety_model(m)
+        )
+    ]