face: WebSocket listener and transport

[yoursunny]

This change implements a WebSocket listener in YaNFD. It supports both unencrypted "ws" scheme and TLS-encrypted "wss" scheme.

This change has been tested with NDNts @ndn/ws-transport package.

Test instructions for "ws" scheme:

1. In yanfd.toml, set faces.websocket.enabled=true.
2. Start YaNFD.
3. Start ndnpingserver and connect it to YaNFD.
4. Checkout https://github.com/yoursunny/NDNts-starter/tree/webpack-js-simple revision 90371b8b3ccd5a2affb5b3f81c7347e3b941a8c8
5. npm install
6. Modify src/main.js:
   • Add at the top:

     import { WsTransport } from "@ndn/ws-transport";

   • Change await connectToNetwork(); to:

     const face = await WsTransport.createFace({}, "ws://localhost:9696");
     face.addRoute(new Name("/"));

7. npm run serve and open http://localhost:3333
8. Enter the name prefix of ndnpingserver and click ping button. You should see responses.

Test instructions for "wss" scheme are similar to above, but:

1. You need a publicly accessible server and a trusted TLS certificate.
2. In yanfd.toml, set faces.websocket.tls_enabled=true, and enter the path to TLS certificate (it should be the "fullchain" file from acme.sh or similar) and TLS key.
3. Enter a "wss" URI in place of ws://localhost:9696.