svm: Add test cases around NMI injection with HLT

This test checks for NMI delivery to L2 and
intercepted NMI (VMEXIT_NMI) delivery to L1
during an active HLT.

Signed-off-by: Cathy Avery <cavery@redhat.com>
Message-Id: <20200409133247.16653-3-cavery@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>