Add JS equivalent of libp2p-echo example

[backkem]

Add JS equivalent of libp2p-echo example to show off compatibility.

[tobowers]

Is there any example for adding the js to a libp2p node? I'm getting invalid multiaddr from bootstrap

[backkem]

Hi @tobowers, I'm not all to familiar with js-libp2p. Maybe @vasco-santos can help us out with setting up a compatibility test.

[tobowers]

Would really love this - I'm seeing a lot of errors trying to get the two to talk.

[tobowers]

fwiw - I don't think the current code works with libp2p, at least browser? However, getting rid of all the internal mux here and switching it around to use the transport.Upgrader has seemed to work.

[backkem]

There is a lower level integration test between the JavaScript and Go variant in examples/standalone. I'm not sure why it would not work when plugged into libp2p.

FYI, pion/webrtc supports compiling to WASM. One thing the 0x guys have been trying is to run go-libp2p both naively and in the browser using WASM. That way you only need one codebase. This effort isn't complete thought.