Add WebRTC Direct Transport

[D4nte]

Problem

The only js-waku<>nim-waku transport currently support is secure websocket.
For users to use secure websocket in the browser without having to hack into their about:config, the nwaku node needs to use a domain certificate for the wss connection.

Which means the nwaku node operator needs to:

• Acquire a domain name
• Set it up
• Acquire a domain name certificate (e.g. letsencrypt)
• Pass the result cert and key to nwaku

This creates friction for the node operator.

Solution

WebRTC Direct enables a web app to connect to a remote node without the need of a SSL certificate.

The node operator just need to have a port open for incoming connections.

Check out this PoC: waku-org/js-waku#588 where js-waku is used in the browser to connect to a remote NodeJS application.

Notes

• js-libp2p webrtc direct example code: https://github.com/libp2p/js-libp2p/blob/master/examples/webrtc-direct/listener.js
• js-lipp2p webrtc direct implementation: https://github.com/libp2p/js-libp2p-webrtc-direct
• go-libp2p webrtc direct implementation: https://github.com/libp2p/go-libp2p-webrtc-direct

[Menduist]

Note that nim-libp2p won't handle it any time soon, see vacp2p/nim-libp2p#698
It's currently not on our roadmap, and need multiple months of work. If waku needs it, we'll probably have to give it to a new hire