[V1] Use pickle for serializing EngineCoreRequest & Add multimodal inputs to EngineCoreRequest (#10245)

Signed-off-by: Woosuk Kwon <woosuk.kwon@berkeley.edu>

vllm/v1/serial_utils.py

@@ -0,0 +1,10 @@
+import pickle
+
+
+class PickleEncoder:
+
+    def encode(self, obj):
+        return pickle.dumps(obj)
+
+    def decode(self, data):
+        return pickle.loads(data)