[Model] feat: FastGen DMD2-distilled Wan 2.1 pipelines (T2V, I2V) (#2749)

Signed-off-by: ayushag <ayushag@nvidia.com>

vllm_omni/diffusion/models/utils.py

@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from __future__ import annotations
+
+import json
+import os
+
+
+def _load_json(model_path: str, filename: str, local_files_only: bool = True) -> dict:
+    """Load a JSON config file from a local path or HuggingFace Hub repo."""
+    if local_files_only:
+        path = os.path.join(model_path, *filename.split("/"))
+        with open(path) as f:
+            return json.load(f)
+    else:
+        from huggingface_hub import hf_hub_download
+
+        cached = hf_hub_download(repo_id=model_path, filename=filename)
+        with open(cached) as f:
+            return json.load(f)