feat: Mounting PVC into Workspace within Subpath

[tolusha]

What does this PR do?

• Introduces a new annotation controller.devfile.io/mount-sub-path that can be set on PVCs labeled for automounting (controller.devfile.io/mount-to-devworkspace: "true").
• When this annotation is present, the PVC volume mount uses the specified subPath, mounting a subdirectory within the PVC instead of the root.

What issues does this PR fix or reference?

eclipse-che/che#23683

Is it tested? How?

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  annotations:
    controller.devfile.io/mount-path: /home/user/subpath
    controller.devfile.io/mount-sub-path: subpath
  labels:
    controller.devfile.io/mount-to-devworkspace: "true"
  name: devworkspace-subpath
  namespace: admin-che
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi

PR Checklist

• E2E tests pass (when PR is ready, comment /test v8-devworkspace-operator-e2e, v8-che-happy-path to trigger)
  • v8-devworkspace-operator-e2e: DevWorkspace e2e test
  • v8-che-happy-path: Happy path for verification integration with Che

[rohanKanojia]

Tested and works as expected!

oc get pod workspace4e61cbe77de44f3c-8686d5c5fc-lcg2g \                                             devfile/devworkspace-operator (pullRequest1595 ⚡) rohan-20y4s1qe0p
  -n openshift-operators \
  -o jsonpath='{.spec.containers[0].volumeMounts[?(@.name=="devworkspace-subpath")]}{"\n"}'        
{"mountPath":"/home/user/subpath","name":"devworkspace-subpath","subPath":"subpath"}

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: akurinnoy, rohanKanojia, tolusha
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