* lisp/net/socks.el: Use lexical-binding and process properties

* lisp/net/socks.el: Use lexical-binding and process properties

Remove unneeded requires.  Better following commenting conventions.
(socks-connections): Remove (use process properties instead).
(socks-wait-for-state-change): Make it a function.
(open-network-stream): Use an advice when overriding.
(socks-send-command): Avoid string-make-unibyte.
(socks--open-network-stream): New function (extracted from
socks-open-network-stream).
(socks-open-network-stream): Rewrite using it.