feat(lite): placeholders for pool/host/VM name_label (#6391)

Some objects may have an empty `name_label`. This is to avoid confusion in the
tree view.

@xen-orchestra/lite/src/components/infra/InfraHostItem.vue

@@ -5,7 +5,7 @@
       :icon="faServer"
       :route="{ name: 'host.dashboard', params: { uuid: host.uuid } }"
     >
-      {{ host.name_label }}
+      {{ host.name_label || '(Host)' }}
       <template #actions>
         <InfraAction
           :icon="isExpanded ? faAngleDown : faAngleUp"

@xen-orchestra/lite/src/components/infra/InfraPoolList.vue

@@ -7,7 +7,7 @@
         :route="{ name: 'pool.dashboard', params: { uuid: pool.uuid } }"
         current
       >
-        {{ pool.name_label }}
+        {{ pool.name_label || '(Pool)' }}
       </InfraItemLabel>
 
       <InfraHostList />

@xen-orchestra/lite/src/components/infra/InfraVmItem.vue

@@ -5,7 +5,7 @@
       :icon="faDisplay"
       :route="{ name: 'vm.console', params: { uuid: vm.uuid } }"
     >
-      {{ vm.name_label }}
+      {{ vm.name_label || '(VM)' }}
       <template #actions>
         <InfraAction>
           <PowerStateIcon :state="vm?.power_state" />