tls: accept array of protocols in TLSSocket

Brings the ALPNProtocols & NPNProtocols options of TLSSocket in line
with the documentation. i.e. an array of strings for protocols may be
used, not only a buffer.

PR-URL: https://github.com/nodejs/node/pull/16655
Fixes: https://github.com/node/issues/16643


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>