feat(storagecluster): add checksum validation fields

[boddumanohar]

fixes: #433

Exposes sbcli's inline CRC checksum validation (silent-data-error protection, design ref TD.100226.1) as cluster-level StorageCluster spec fields.

apiVersion: storage.simplyblock.io/v1alpha1
kind: StorageCluster
spec:
  enableChecksumValidation: true
  enableAtomic4kWrites: true  # only on 512B devices that are 4K-atomic, e.g., AWS NVMe

• enableChecksumValidation enables checksum validation on every I/O. This alone is enough; on drives with a native 4K logical block size it is the normal case.
• enableAtomic4kWrites sets the backend's cv_ignore_block_size, letting checksum validation run on devices that report a 512B logical block size but guarantee 4K write atomicity. It requires enableChecksumValidation; with checksums off, the backend never sends the parameter at all.
• Both fields are immutable once set, matching the backend: the checksum method is baked into each device's bdev_alceml_create call at cluster-create time and never re-applied.

The operator maps these Kubernetes-facing fields into ClusterAddParams for POST /api/v2/clusters/ as inline_checksum and atomic_4k, matching the merged sbcli API fields.

Accepted combinations

enableChecksumValidation	enableAtomic4kWrites	Result
unset	unset	checksums off
false	false	checksums off
true	false	checksums on, the normal case
true	true	checksums on + 4K-atomic escape hatch
false/unset	true	rejected