tools: support validating SEV-ES initial vCPU state measurements

tools: support validating SEV-ES initial vCPU state measurements

With the SEV-ES policy the VMSA state of each vCPU must be included in
the measured data. The VMSA state can be generated using the 'sevctl'
tool, by telling it a QEMU VMSA is required, and passing the hypevisor's
CPU SKU (family, model, stepping).

Reviewed-by: Cole Robinson <crobinso@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>