dns/knot-resolver: upgrade 4.2.2 -> 5.0.1

• for changes from 4.x to 5.x which might cause trouble during upgrades, please read: https://knot-resolver.readthedocs.io/en/stable/upgrading.html

PR: 243948
Submitted by: Leo Vandewoestijne <freebsd@dns.company> (maintainer)
Relnotes: https://www.knot-resolver.cz/2020-01-27-knot-resolver-5.0.0.html

		https://www.knot-resolver.cz/2020-02-05-knot-resolver-5.0.1.html