Reasoning parser (#4000)

Co-authored-by: Lucas Pickup <lupickup@microsoft.com>

python/sglang/srt/managers/io_struct.py

@@ -678,6 +678,12 @@ class ParseFunctionCallReq:
     )
 
 
+@dataclass
+class SeparateReasoningReqInput:
+    text: str  # The text to parse.
+    reasoning_parser: str  # Specify the parser type, e.g., "deepseek-r1".
+
+
 @dataclass
 class VertexGenerateReqInput:
     instances: List[dict]