Add a function that checks whether a DNSKEY, CDNSKEY, or CDS record
belongs to a key that is being used for signing.
(cherry picked from commit 3b6e9a5fa7)
Add a function that checks whether a DNSKEY, CDNSKEY, or CDS record
belongs to a key that is being used for signing.
(cherry picked from commit 3b6e9a5fa7)