feat: Add VolumePolicy support for PVC Phase conditions to allow skipping Pending PVCs

This commit implements VolumePolicy support for PVC Phase conditions, resolving
vmware-tanzu/velero#7233 where backups fail with ''PVC has no volume backing this claim''
for Pending PVCs.

Changes made:
- Extended VolumePolicy API to support PVC phase conditions
- Added pvcPhaseCondition struct with matching logic
- Modified getMatchAction() to evaluate policies for unbound PVCs before returning errors
- Added case to GetMatchAction() to handle PVC-only scenarios (nil PV)
- Added comprehensive unit tests for PVC phase parsing and matching

Users can now skip Pending PVCs through volume policy configuration:
  apiVersion: v1
  kind: ConfigMap
  metadata:
    name: volume-policy
    namespace: velero
  data:
    policy.yaml: |
      version: v1
      volumePolicies:
      - conditions:
          pvcPhase: [Pending]
        action:
          type: skip

chore: rename changelog file to match PR #9166

Renamed changelogs/unreleased/7233-claude to changelogs/unreleased/9166-claude
to match the opened PR at https://github.com/vmware-tanzu/velero/pull/9166

docs: Add PVC phase condition support to VolumePolicy documentation

- Added pvcPhase field to YAML template example
- Documented pvcPhase as a supported condition in the list
- Added comprehensive examples for using PVC phase conditions
- Included examples for Pending, Bound, and Lost phases
- Demonstrated combining PVC phase with other conditions

Co-Authored-By: Tiger Kaovilai <kaovilai@users.noreply.github.com>

changelogs/unreleased/9166-claude

@@ -0,0 +1 @@
+Add VolumePolicy support for PVC Phase conditions to allow skipping Pending PVCs