vmm: Deprecate MemoryZoneConfig::file

Remove from the documentation and API definition but continue support
using the field (with a deprecation warning.)

See: #4837

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

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

@@ -668,8 +668,6 @@ components:
           type: integer
           format: int64
           default: 512 MB
-        file:
-          type: string
         mergeable:
           type: boolean
           default: false

vmm/src/config.rs

@@ -2015,6 +2015,10 @@ impl VmConfig {
 
         if let Some(zones) = &self.memory.zones {
             for zone in zones.iter() {
+                if zone.file.is_some() {
+                    warn!("MemoryZoneConfig::file is deprecated and will be removed in future release (#4837)");
+                }
+
                 let id = zone.id.clone();
                 Self::validate_identifier(&mut id_list, &Some(id))?;
             }