virt-host-validate: Detect SEV-ES and SEV-SNP

virt-host-validate: Detect SEV-ES and SEV-SNP

With a simple cpuid (Section "E.4.17 Function
8000_001Fh—Encrypted Memory Capabilities" in "AMD64 Architecture
Programmer’s Manual Vol. 3") we can detect whether CPU is capable
of running SEV-ES and/or SEV-SNP guests. Report these in
virt-host-validate tool.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>