Add configurable sockopt for raw router sockets

[dr7ana]

Since v3.3, libzmq has had the option for ZMQ_ROUTER_RAW, where ZMQ framing is not added to read/write data. This PR introduces the ability to set that using the already implemented logic as follows:

zmq::context_t ctx;
zmq::socket_t raw_router(ctx, zmq::socket_type::router);
raw_router.set(zmq::sockopt::router_raw, 1);

[dr7ana]

@gummif or @stephanlachnit, would you mind approving the workflow on this when you get a chance please?