libp2p-go: Add support for WebRTC testing using libp2p-go

[lexnv]

This PR adds a libp2p-go equivalent of the litep2p-perf protocol.

This will allow us to stress-test our substreams and serve as a compatibility check to ensure our implementation remains compliant with the WebRTC spec

Testing Done

Running at the moment with lexnv/add-libp2p-go which includes:

• webrtc: Decode webrtc message from multiple SCTP messages paritytech/litep2p#594
• fix(webrtx): ICE issue + substream shutdown procedure paritytech/litep2p#586
• feat(webrtc): producer backpressure paritytech/litep2p#575

Litep2p

RUST_LOG=info cargo run -p litep2p-perf --release -- server \
   --listen-address "/ip4/127.0.0.1/udp/33333/webrtc-direct" \
   --node-key "secret" \
   --transport-layer webrtc
   
2026-05-25T10:42:30.319671Z  INFO litep2p_perf: Event: ConnectionEstablished { peer: PeerId("12D3KooWK5cpS16bj7VQQXzS5xWYyGhUvt6mKSqm7tvL39WPYYQe"), endpoint: Listener { address: /ip4/127.0.0.1/udp/48086/webrtc-direct/certhash/uEiCVH9ycEm6Nl-l04x3WfPLmcyWfIDqscnuQzVYQbQLe3w/p2p/12D3KooWK5cpS16bj7VQQXzS5xWYyGhUvt6mKSqm7tvL39WPYYQe, connection_id: ConnectionId(0) } }
2026-05-25T10:42:30.319936Z  WARN str0m: Drop BufferedAmountLow for id: 0
2026-05-25T10:42:30.322256Z  WARN str0m: Drop ChannelData event for id: 2
2026-05-25T10:42:30.322269Z  WARN str0m: Drop ChannelData event for id: 2

2026-05-25T10:42:35.323384Z  INFO litep2p_perf: Event: ConnectionClosed { peer: PeerId("12D3KooWK5cpS16bj7VQQXzS5xWYyGhUvt6mKSqm7tvL39WPYYQe"), connection_id: ConnectionId(0) }
2026-05-25T10:42:35.323501Z  INFO litep2p-perf: connection closed peer=PeerId("12D3KooWK5cpS16bj7VQQXzS5xWYyGhUvt6mKSqm7tvL39WPYYQe")

Libp2p-go

cd libp2p-go 
  go mod tidy
  go run . \
        --server-address "/ip4/127.0.0.1/udp/33333/webrtc-direct/certhash/uEiCnBkZwj-Y-JhhThrKDhDuQxwPOy_3vWsCfavSDha4Ccg/p2p/12D3KooWBpZHDZu7YSbvPaPXKhkRNJvR7MkTJMQQAVBKx9mCqz3q" \
        --upload-bytes 1048576 \
        --download-bytes 1048576
        
        
2026/05/25 10:42:39 local peer id: 12D3KooWDKuqsVg7jpgWErHDrZayuUCys5U5eCtrLMcuawccmVJL
2026/05/25 10:42:39 dialing /ip4/127.0.0.1/udp/33333/webrtc-direct/certhash/uEiCnBkZwj-Y-JhhThrKDhDuQxwPOy_3vWsCfavSDha4Ccg/p2p/12D3KooWBpZHDZu7YSbvPaPXKhkRNJvR7MkTJMQQAVBKx9mCqz3q
2026/05/25 10:42:39 connected to 12D3KooWBpZHDZu7YSbvPaPXKhkRNJvR7MkTJMQQAVBKx9mCqz3q
2026/05/25 10:42:39 Uploaded 1.00 MiB in 0.0465s bandwidth 171.92 Mbit/s
2026/05/25 10:42:39 Downloaded 1.00 MiB in 0.0215s bandwidth 372.63 Mbit/s