Fix examples and modify new_node

- Fix examples `chat.py` and `echo.py`
    - Use trio directly, instead of `trio-asyncio`
    - Remove redundant code
- Change entry API `new_node` to `new_host_trio`

libp2p/network/network_interface.py

@@ -1,6 +1,7 @@
 from abc import ABC, abstractmethod
 from typing import TYPE_CHECKING, Dict, Sequence
 
+from async_service import ServiceAPI
 from multiaddr import Multiaddr
 
 from libp2p.network.connection.net_connection_interface import INetConn
@@ -70,3 +71,7 @@ class INetwork(ABC):
     @abstractmethod
     async def close_peer(self, peer_id: ID) -> None:
         pass
+
+
+class INetworkService(INetwork, ServiceAPI):
+    ...