Add new rpmsign-sequoia and rpmsign-gnupg subpackages which can be
used to switch between the two OpenPGP implementations for signing,
rpm-sign-libs just requires one of them to be present.
It's worth noting that unlike GnuPG, Sequoia doesn't accept names or
email addresses as the signer identifier, one needs to supply the actual key
fingerprint.
Resolves: RHEL-56363
