tunnel-sink-new: add a rewrite of module-tunnel using libpulse
The old tunnel module duplicates functionality that is in libpulse,
due to implementing the native protocol, and the protocol code in
the old tunnel module tends to get broken every now and then, because
people forget to update the tunnel module protocol implementation
when changing the native protocol. module-tunnel-sink-new avoids this
problem by using libpulse to communicate with the remote server.