【Feature】add fd plugins && rm model_classes (#3123)

* add fd plugins && rm model_classed

* fix reviews

* add docs

* fix

* fix unitest ci

fastdeploy/plugins/utils.py

@@ -0,0 +1,61 @@
+"""
+# 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 typing import Any, Callable
+
+from fastdeploy import envs
+from fastdeploy.utils import llm_logger as logger
+
+plugins_loaded = False
+
+
+def load_plugins_by_group(group: str) -> dict[str, Callable[[], Any]]:
+    import sys
+
+    if sys.version_info < (3, 10):
+        from importlib_metadata import entry_points
+    else:
+        from importlib.metadata import entry_points
+
+    allowed_plugins = envs.FD_PLUGINS
+
+    discovered_plugins = entry_points(group=group)
+    if len(discovered_plugins) == 0:
+        logger.info("No plugins for group %s found.", group)
+        return {}
+
+    logger.info("Available plugins for group %s:", group)
+    for plugin in discovered_plugins:
+        logger.info("- %s -> %s", plugin.name, plugin.value)
+
+    if allowed_plugins is None:
+        logger.info(
+            "All plugins in this group will be loaded. " "You can set `FD_PLUGINS` to control which plugins to load."
+        )
+
+    plugins = dict[str, Callable[[], Any]]()
+    for plugin in discovered_plugins:
+        if allowed_plugins is None or plugin.name in allowed_plugins:
+            if allowed_plugins is not None:
+                logger.info("Loading plugin %s", plugin.name)
+
+            try:
+                func = plugin.load()
+                plugins[plugin.name] = func
+            except Exception:
+                logger.exception("Failed to load plugin %s", plugin.name)
+
+    return plugins