feat: Add identify-push raw format support and yamux logging improvements

- Add comprehensive integration tests for identify-push protocol
- Support both raw protobuf and varint message formats
- Improve yamux logging integration with LIBP2P_DEBUG
- Fix RawConnError handling to reduce log noise
- Add Ctrl+C handling to identify examples
- Enhance identify-push listener/dialer demo

Fixes: #784

libp2p/identity/identify/identify.py

@@ -113,7 +113,7 @@ def parse_identify_response(response: bytes) -> Identify:
 
 
 def identify_handler_for(
-    host: IHost, use_varint_format: bool = False
+    host: IHost, use_varint_format: bool = True
 ) -> StreamHandlerFn:
     async def handle_identify(stream: INetStream) -> None:
         # get observed address from ``stream``