dns: deprecate passing falsy hostname to dns.lookup

We can `dns.lookup` a falsy `hostname` like `dns.lookup(false)`
for the reason of backwards compatibility long before(see #13119
for detail). This behavior is undocumented and seems useless in
real world apps.

We could also make invalid `hostname` throw in the future and the
change might be semver-major.

Fixes: https://github.com/nodejs/node/issues/13119

PR-URL: https://github.com/nodejs/node/pull/23173


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>