vmm: Add device_id field to NUMA configuration

Add an optional device_id string field to NumaConfig for identifying
PCI devices associated with a NUMA node. This is used by the Generic
Initiator support to map devices to their proximity domain.

Update OpenAPI spec (cloud-hypervisor.yaml) to include the
new device_id field in the NumaConfig schema.

The device_id is optional and parsed from the --numa parameter:
  --numa "device_id=<device_id>,distances=[...],..."

The optional field is accepted but not used.

Signed-off-by: Saravanan D <saravanand@crusoe.ai>

vmm/src/vm_config.rs

@@ -685,6 +685,8 @@ pub struct NumaConfig {
     pub memory_zones: Option<Vec<String>>,
     #[serde(default)]
     pub pci_segments: Option<Vec<u16>>,
+    #[serde(default)]
+    pub device_id: Option<String>,
 }
 
 /// Errors describing a misconfigured payload, i.e., a configuration that