Storage volumes: show actual used space (not only allocated) and allow PVC expansion from the platform UI

As a platform administrator you can use the Total resource usage → Volumes page to keep storage under control. The table lists every PVC with its provisioned capacity ("PVC size"), phase, service, service instance and access mode, but it only shows allocated capacity, never how much of each volume is actually consumed. From this page the administrator cannot tell which volumes are close to full (e.g. Db2 backup, DataStage temp, IBM Knowledge Catalog Postgres, RabbitMQ, etc.). In practice a problem is only discovered when a pod starts failing because its volume is full. The top summary shows only a total size (e.g. 2648.92 GB), again allocated, with no notion of real usage.

Current workaround:
The administrator has to log into the underlying OpenShift/Kubernetes cluster with cluster-admin rights to inspect real usage via CLI/monitoring (Prometheus, oc adm top, df inside pods) and, when more space is needed, edit the PVC spec to resize it, only where the storage class has allowVolumeExpansion=true. All of this happens outside the Software Hub console and requires cluster-level privileges.

Where the platform administrator has OpenShift cluster access and the cluster monitoring stack is enabled, the same information and action exist one layer below, in the OpenShift console (Storage → PersistentVolumeClaims): the PVC detail page shows real utilization, and Actions → Expand PVC resizes the volume where the storage class allows expansion. However this path is not available to all customers. In managed OpenShift, as-a-service offerings, or enterprises with strict separation of duties, the Software Hub administrator often has no OpenShift access at all; and where cluster/volume monitoring is not configured, the real usage metric is not exposed even in OpenShift. For those customers the Software Hub Total resource usage page is the only surface they have, and today it shows allocated capacity only, with no way to see real usage or to resize.

Proposed solution:

1. Add "Used (GB)" and "Utilization %" columns to the Volumes table (used vs allocated), with a visual bar / colour threshold.
2. Show total used vs total allocated in the summary at the top of the page (today only total allocated size is shown).
3. Allow sorting/filtering by utilization and configurable alert thresholds (e.g. notify at 80% / 90%).
4. Add a UI action to expand a PVC in place for storage classes that support volume expansion, gated by appropriate RBAC, so the platform admin can self-serve without cluster CLI access.

Benefits / value:

• Prevents outages caused by full volumes and reduces mean-time-to-detect.
• Enables capacity planning from a single pane of glass, instead of correlating console + cluster monitoring.
• Improves operational efficiency by removing the need for cluster-admin CLI operations to resize storage.