PoC of WebRTC signalling exchange through @waku/noise

[weboko]

Showcasing establishment of RTC connection through Waku Noise.

This PR TODO:

• prettify code

WebRTC TODO:

• handle STUN (offer/answer) in a decentralised way: https://github.com/libp2p/specs/tree/master/identify#the-identify-message. Essentially there should be a way to gather info from the network about particular client and build STD string without involving some central server.
• signalling server (TURN) to allow two clients to communicate even if NAT does not allow so. Worst case we can just send messages through Waku :)
• create NoiseRTC abstraction to manage RTC connection and initiate it trough Noise data channel.

Covers waku-org/js-waku#20

[fryorcraken]

Please add a README to clarify the purpose of this example and its state (work in progress)
Also, is there a way to get more feedback that the RTC connection is successful? I guess checking the about:webrtc tab helps.

Finally, currently need to confirm an auth code on both side.

However, in a scenario where I know the peer id of the other peer, meaning they can prove their identity by signing a message with their private key, can we skip the authocode check? Or, is that scenario not catered for yet in the RFC?

Because in the case of using webrtc to setup more connection between browser node, I do not expect manual/human intervention (note that the remote peer address is expected to be retrieved in a ENR form which is signed).

Cc @kaiserd @richard-ramos