repl: hide editor mode if not used in a terminal

The editor mode is only useable when used as terminal. Hide it from
the user in case the repl terminal option is not set.

PR-URL: https://github.com/nodejs/node/pull/26240


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>