tools: non-Ascii linter for /lib only

Non-ASCII characters in /lib get compiled into the node binary,
and may bloat the binary size unnecessarily. A linter rule may
help prevent this.

PR-URL: https://github.com/nodejs/node/pull/18043
Fixes: https://github.com/nodejs/node/issues/11209


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>