feat(module): add Virtualization Overview dashboard and VM info metric

[fl64]

Description

• Add new metric d8_virtualization_virtualmachine_info with applied_virtualmachineclass and node labels
• Add "Virtualization Overview" dashboard with cluster-wide VM statistics
• Move VM and VMs dashboards to virtualization folder

Why do we need it, and what problem does it solve?

Operators need centralized visibility into virtualization resources across the cluster — VM distribution by VMClass, storage usage by StorageClass, and per-namespace breakdown. The new metric shows which VMClass is actually applied to running VMs (may differ from spec before restart).

What is the expected result?

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: module
type: feat
summary: add Virtualization Overview dashboard and VM info metric