Add Volumes nav property to Storage template

The Storage emulator template did not include the Volumes navigation
property. Without this property, a client cannot locate the Volumes
collection.

Adds the Volumes navigation property to the Storage emulator template.

Change-Id: Iac05c0ee131cc077af43fea6c93d342ce11a81cd
Story: 2003514
Task: 40776

releasenotes/notes/add-volume-collection-to-storage-template-b673a7acfbb1a03e.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Adds the ``Volumes`` navigation property to the ``Storage`` emulator
+    template.

sushy_tools/emulator/templates/storage.json

@@ -47,6 +47,9 @@
         {% endfor -%}
     ],
     {% endif -%}
+    "Volumes": {
+        "@odata.id": {{ "/redfish/v1/Systems/%s/Storage/%s/Volumes"|format(identity, storage['Id'])|tojson }}
+    },
     "@odata.context": "/redfish/v1/$metadata#Storage.Storage",
     "@odata.id": {{ "/redfish/v1/Systems/%s/Storage/%s"|format(identity, storage['Id'])|tojson }}
 }