feat(ml): round-robin device assignment (#13237)

* round-robin device assignment

* docs and tests

clarify doc

machine-learning/app/test_main.py

@@ -210,10 +210,24 @@ class TestOrtSession:
         session = OrtSession(model_path, providers=["OpenVINOExecutionProvider", "CPUExecutionProvider"])
 
         assert session.provider_options == [
-            {"device_type": "GPU", "precision": "FP32", "cache_dir": "/cache/ViT-B-32__openai/openvino"},
+            {"device_type": "GPU.0", "precision": "FP32", "cache_dir": "/cache/ViT-B-32__openai/openvino"},
             {"arena_extend_strategy": "kSameAsRequested"},
         ]
 
+    def test_sets_device_id_for_openvino(self) -> None:
+        os.environ["MACHINE_LEARNING_DEVICE_ID"] = "1"
+
+        session = OrtSession("ViT-B-32__openai", providers=["OpenVINOExecutionProvider"])
+
+        assert session.provider_options[0]["device_type"] == "GPU.1"
+
+    def test_sets_device_id_for_cuda(self) -> None:
+        os.environ["MACHINE_LEARNING_DEVICE_ID"] = "1"
+
+        session = OrtSession("ViT-B-32__openai", providers=["CUDAExecutionProvider"])
+
+        assert session.provider_options[0]["device_id"] == "1"
+
     def test_sets_provider_options_kwarg(self) -> None:
         session = OrtSession(
             "ViT-B-32__openai",