function deconstructPacket(packet) {
    const buffers = [];
    const packetData = packet.data;
    const pack = packet;
    pack.data = _deconstructPacket(packetData, buffers);
    pack.attachments = buffers.length; // number of binary 'attachments'
    return { packet: pack, buffers: buffers };
}
Replaces every Buffer | ArrayBuffer | Blob | File in packet with a numbered placeholder.

@param {Object} packet - socket.io event packet
@return {Object} with deconstructed packet and list of buffers
@public