[plugin] Custom model_runner/model support (#3186)

* support custom model&&model_runner

* fix merge

* add test && update doc

* fix codestyle

* fix unittest

* load model in rl

test/plugins/fd_add_dummy_model/__init__.py

@@ -1,6 +1,21 @@
+# Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 from paddleformers.transformers import PretrainedModel
 
 from fastdeploy import ModelRegistry
+from fastdeploy.config import ErnieArchitectures
 from fastdeploy.model_executor.models.model_base import ModelForCasualLM
 
 
@@ -31,5 +46,7 @@ class MyModelForCasualLM(ModelForCasualLM):
 
 def register():
     if "MyModelForCasualLM" not in ModelRegistry.get_supported_archs():
+        if MyModelForCasualLM.name().startswith("Ernie"):
+            ErnieArchitectures.register_ernie_model_arch(MyModelForCasualLM)
         ModelRegistry.register_model_class(MyModelForCasualLM)
         ModelRegistry.register_pretrained_model(MyPretrainedModel)