[Core] Interface for accessing model from VllmRunner (#10353)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

tests/models/embedding/language/test_embedding.py

@@ -62,10 +62,13 @@ def test_models(
                      max_model_len=None,
                      **vllm_extra_kwargs) as vllm_model:
         vllm_outputs = vllm_model.encode(example_prompts)
+
         # This test is for verifying whether the model's extra_repr
         # can be printed correctly.
-        print(vllm_model.model.llm_engine.model_executor.driver_worker.
-              model_runner.model)
+        def print_model(model):
+            print(model)
+
+        vllm_model.apply_model(print_model)
 
     check_embeddings_close(
         embeddings_0_lst=hf_outputs,