[Core] feat: Implement Priority Scheduling in V1 Engine (#19057)

Signed-off-by: amit <amit.man@gmail.com>
Co-authored-by: Roger Wang <Rogerw0108@gmail.com>

vllm/v1/engine/processor.py

@@ -219,8 +219,6 @@ class Processor:
         # TODO(woosuk): Support encoder-decoder models.
         self._validate_lora(lora_request)
         self._validate_params(params, lora_request)
-        if priority != 0:
-            raise ValueError("V1 does not support priority yet.")
         if trace_headers is not None:
             raise ValueError("V1 does not support tracing yet.")
         if prompt_adapter_request is not None:
@@ -340,6 +338,7 @@ class Processor:
             arrival_time=arrival_time,
             lora_request=lora_request,
             cache_salt=decoder_inputs.get("cache_salt"),
+            priority=priority,
             data_parallel_rank=data_parallel_rank,
         )