Refactor message sending architecture and implement legacy driver support

- Removed UniversalMessageSender from group_generator.py and private_generator.py.
- Updated PlatformIOManager to manage legacy send drivers and ensure send pipeline readiness.
- Enhanced LegacyPlatformDriver to utilize prepared messages for sending.
- Refactored send_service to unify message sending logic and integrate with Platform IO.
- Added regression tests for Platform IO legacy driver and send service functionality.

src/common/message_server/server.py

@@ -21,7 +21,7 @@ class Server:
         self._server: Optional[UvicornServer] = None
         self.set_address(host, port)
 
-    def register_router(self, router: APIRouter, prefix: str = ""):
+    def register_router(self, router: APIRouter, prefix: str = ""): 
         """注册路由
 
         APIRouter 用于对相关的路由端点进行分组和模块化管理：