[V1][Perf] Faster incremental detokenization (vllm-project#15137)

Signed-off-by: Nick Hill <[email protected]>

Author: njhill

requirements/test.txt

@@ -692,6 +692,10 @@ tokenizers==0.21.1
     # via
     #   -r requirements/test.in
     #   transformers
+tomli==2.2.1
+    # via schemathesis
+tomli-w==1.2.0
+    # via schemathesis
 torch==2.6.0
     # via
     #   -r requirements/test.in