Proposal: Websocket API for P2P communications

[ohager]

As recently proposed (and already running experimental implementation) in SIP50 it could be interesting to add a web socket communication for P2P communication. This FR does not provide any technical details yet,... but I will analyze how P2P works and check how to enhance the API using WS.

The motivation is similar to SIP50. We might expect a lightweight event driven full-duplex communication which should be usually favored over common request/response communication.