[Feature] Support EP prefill with num_worst_tokens (#6574)

* support num worst tokens

* support num worst tokens

* fix build error

* support num worst tokens: fix errors

* support num worst tokens: fix feild

* support num worst tokens: delete requiements

* replace permute and depermute op by pure cuda

* replace permute and depermute op by pure cuda

* fix ci

* fix op

* fix nan

* fix code style

---------

Co-authored-by: YuBaoku <49938469+EmmonsCurse@users.noreply.github.com>

fastdeploy/engine/args_utils.py

@@ -546,6 +546,11 @@ class EngineArgs:
     Flag to enable entropy output. Default is False (disabled).
     """
 
+    ep_prefill_use_worst_num_tokens: bool = False
+    """
+    Flag to enable prefill_use_worst_num_tokens. Default is False (disabled).
+    """
+
     def __post_init__(self):
         """
         Post-initialization processing to set default tokenizer if not provided.
@@ -1060,6 +1065,12 @@ class EngineArgs:
             default=EngineArgs.shutdown_comm_group_if_worker_idle,
             help="Shutdown communication group when worker is idle.",
         )
+        parallel_group.add_argument(
+            "--ep-prefill-use-worst-num-tokens",
+            action="store_true",
+            default=EngineArgs.ep_prefill_use_worst_num_tokens,
+            help="Enable prefill use worst num tokens for EP.",
+        )
 
         # Load group
         load_group = parser.add_argument_group("Load Configuration")