vmm: support injecting NMI

Inject NMI interrupt when needed, by call ioctl KVM_NMI.

Signed-off-by: Yi Wang <foxywang@tencent.com>

vmm/src/api/openapi/cloud-hypervisor.yaml

@@ -405,6 +405,13 @@ paths:
         405:
           description: The VM instance could not be coredumped because it is not booted.
 
+  /vmm.nmi:
+    put:
+      summary: Inject an NMI.
+      responses:
+        204:
+          description: The NMI successfully injected.
+
   /vm.restore:
     put:
       summary: Restore a VM from a snapshot.