test: add tests for dnsPromises.lookup

Added tests for dnsPromises.lookup to increase coverage and test
`onlookup()` and `onlookupall()` methods.

PR-URL: https://github.com/nodejs/node/pull/21559


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>