Draft: Use .active_sockets list instead of uv_walk to shutdown nmsockets
Since we are now keeping the list of active sockets for each worker, we don't have to rely on uv_walk() to shutdown active networking sockets; use the .active_sockets to shutdown all types of active sockets - UDP, TCP, TLSStream, StreamDNS and HTTP sockets are not shutdown in the natural order. Thus if TLSStream opens a TCP socket, the TLSStream socket will be shutdown first and could cleanup the outer TCP socket as part of its own cleanup procedure.
Closes #4011 (closed)