[PD] Add control to slow down a server (#5572)

python/sglang/srt/managers/io_struct.py

@@ -790,6 +790,16 @@ class ResumeMemoryOccupationReqOutput:
     pass
 
 
+@dataclass
+class SlowDownReqInput:
+    forward_sleep_time: Optional[float]
+
+
+@dataclass
+class SlowDownReqOutput:
+    pass
+
+
 @dataclass
 class AbortReq:
     # The request id