kvm-unit-test: nSVM: Add alternative (v2) test format for nested guests

  ..so that we can add tests such as VMCB consistency tests, that require
  the tests to only proceed up to the execution of the first guest (nested)
  instruction and do not require us to define all the functions that the
  current format dictates.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>