Include code in unknown error messages

Author: JordonPhillips

codegen/core/src/main/java/software/amazon/smithy/python/codegen/integrations/HttpProtocolGeneratorUtils.java

@@ -149,7 +149,7 @@ public static void generateErrorDispatcher(
                             ${7C|}
 
                             case _:
-                                return $5T(message)
+                                return $5T(f"{code}: {message}")
                     """,
                     errorDispatcher.getName(),
                     transportResponse,