[VMOwnedVolumes][Draft]Core Workflows — Attach, Snapshot, Detach, Snapshot Deletion, Revert Re-adoption

[deepakkinni]

What this PR does / why we need it:
Phase 2 — Workflow A: Attach (Section 7)
Greenfield/Brownfield Branching in BA Controller (A.3) — In cnsnodevmbatchattachment_controller.go, for each new dependent-persistent volume in BA spec, read the parent VM's vmoperator.vmware.com/vm-owned-volumes annotation and check CVI existence/state; if greenfield + CVI CSI_MANAGED, take the new path; otherwise fall through to legacy CnsAttachVolume (AttachMethod=CnsAttach).

CnsUnregisterVolume Call (A.3) — Implement the call to CnsUnregisterVolume(volumeID, targetType=LEGACY_DISK) via cns-lib/volume/manager.go, handling the two-phase PENDING_UNREGISTER result (backingDiskPath, diskUUID) and error cases (snapshots, CBT, linked clone).

CVI Transition + BA Signal + CNS ACK (A.4) — After successful unregister: (1) patch CVI to TRANSFERRING_TO_VM with vmName, vmInstanceUUID, refreshed diskPath, and cvi-protection finalizer; (2) write diskPath/diskUUID and AttachMethod=Reconfig condition on BA status; (3) call AckUnregister to delete the CNS PENDING_UNREGISTER row.

PENDING_UNREGISTER Crash Recovery (A.3/A.4) — On CSI pod restart, scan CNS for volumes in PENDING_UNREGISTER state that correspond to greenfield BA spec entries, and resume from step A.4 (CVI patch, BA update, ACK).

Mid-Attach Cancellation (Section 7.5) — When a volume is removed from vm.spec.volumes while CVI is in TRANSFERRING_TO_VM, drive Workflow C from the transient state: skip ReconfigVM (disk not yet on VM), query vCenter snapshot tree, and re-register FCD back to CSI_MANAGED.

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

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