selftests: kvm: add get_msr_index_features

Test the KVM_GET_MSR_FEATURE_INDEX_LIST
and KVM_GET_MSR_INDEX_LIST ioctls.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20210318145629.486450-1-eesposit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>