[Core] Loading model from S3 using RunAI Model Streamer as optional loader (#10192)

Signed-off-by: OmerD <omer@run.ai>

vllm/engine/arg_utils.py

@@ -316,6 +316,8 @@ class EngineArgs:
             '* "tensorizer" will load the weights using tensorizer from '
             'CoreWeave. See the Tensorize vLLM Model script in the Examples '
             'section for more information.\n'
+            '* "runai_streamer" will load the Safetensors weights using Run:ai'
+            'Model Streamer \n'
             '* "bitsandbytes" will load the weights using bitsandbytes '
             'quantization.\n')
         parser.add_argument(