Support WebSocket packet filters

[hanayashiki]

See commit messages for details.

Example use:

const AnyProxy = require('anyproxy');
const options = {
    port: 8001,
    rule: {
        beforeSendWsMessage: (e, url) => {
            console.log(url, e.data);
        },
        beforeReadWsMessage: (e, url) => {
            console.log(url, e.data);
        }
    },
    webInterface: {
        enable: true,
        webPort: 8002
    },
    throttle: 10000,
    forceProxyHttps: true,
    wsIntercept: true,
    silent: false,
    dangerouslyIgnoreUnauthorized: true,
};


const proxyServer = new AnyProxy.ProxyServer(options);


proxyServer.on('ready', () => { /* */
});
proxyServer.on('error', (e) => { /* */
});
proxyServer.start();

Output:

...
wss://example.com {"a": 0, "b": 1}
wss://example.com {"a": 1, "b": 2}
...

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