fix(vm): mark proxy mediation destinations explicit

Signed-off-by: Drew Newberry <anewberry@nvidia.com>

Author: drew

crates/openshell-driver-vm/src/isolation/backend.rs

@@ -598,6 +598,7 @@ impl NetworkMediationSource for VmNetworkMediation {
         Ok(MediatedConnection {
             stream,
             binary_identity: identity.into_result(),
+            destination: None,
         })
     }
 }