tls: disable RC4, add --cipher-list command line switch

Disable RC4 in the default cipher list

Add the `--cipher-list` command line switch and `NODE_CIPHER_LIST`
environment variable to completely override the default cipher list.

Add the `--enable-legacy-cipher-list` and `NODE_LEGACY_CIPHER_LIST`
environment variable to selectively enable the default cipher list from
previous node.js releases.

Reviewed-By: James M Snell <jasnell@gmail.com>
PR-URL: https://github.com/joyent/node/pull/14413