Support WebRTC data channels

[bajtos]

Many peer-to-peer projects use WebRTC data channels for connectivity. WebRTC became a W3C Recommendation back in 2021 (announcement). It makes sense for Zinnia to support it as part of Zinnia's support for Web Platform APIs.

Deno's tracking issue for adding WebRTC support:

• WebRTC Integrating denoland/deno#1612

[bajtos]

More resources:

• iOS: https://github.com/stasel/WebRTC
• Android: https://github.com/GetStream/webrtc-android
• The official Google implementation: https://webrtc.googlesource.com/src/
• https://github.com/sipsorcery/webrtc-interop
• https://github.com/lerouxrgd/datachannel-rs