Add IPv6 support for IPAddressAllocation CRD and NSX payload

[poojav25]

Add ipAddressType (IPv4/IPv6) and ipv6AllocationPrefixLength handling

• Map CRD enum values to NSX SDK values and populate NSX IpAddressType
  and Ipv6AllocationPrefixLength on the VpcIpAddressAllocation payload
• Add ipAddressType field (IPv4/IPv6, default IPv4) and
  ipv6AllocationPrefixLength field (range 64–128) to IPAddressAllocationSpec
• Disallow ipAddressBlockVisibility when ipAddressType=IPv6 via CRD XValidation
• Disallow allocationSize when ipAddressType=IPv6 via CRD XValidation
• Disallow ipv6AllocationPrefixLength when ipAddressType=IPv4 via CRD XValidation
• ipAddressType and ipv6AllocationPrefixLength are immutable once set
• Omit IpAddressBlockVisibility for IPv6 payloads in builder; keep IPv4
  default behavior unchanged
• Default ipv6AllocationPrefixLength to 64 in builder when field is omitted
• Update compare logic to include IpAddressType and Ipv6AllocationPrefixLength
• Update webhook to reflect new field constraints
• Add/adjust unit tests and stabilize store initialization stubs

Fixes: RBAC marker plural form on SubnetIPReservation controller

Testing done:

-> Create IPv4 Private allocation (regression check)

apiVersion: crd.nsx.vmware.com/v1alpha1
kind: IPAddressAllocation
metadata:
  name: test-ipv4-private
  namespace: svc-tkg-38ilo
spec:
  ipAddressBlockVisibility: Private
  allocationSize: 16
  ipAddressType: IPv4

Result: ALLOCATIONIPS=172.26.0.0/28. IPv4 path unaffected by IPv6 changes.

-> Create IPv6 allocation with explicit prefix length

apiVersion: crd.nsx.vmware.com/v1alpha1
kind: IPAddressAllocation
metadata:
  name: test-ipv6-prefix64
  namespace: test-ipv6-ns
spec:
  ipAddressType: IPv6
  ipv6AllocationPrefixLength: 64

Result: ALLOCATIONIPS=2001:db8::/64, IPV6ALLOCATIONPREFIXLENGTH=64. NSX allocated a /64 from the 2001:db8::/48 external IPv6 block.

-> Create IPv6 allocation with omitted prefix (default /64 via builder)

apiVersion: crd.nsx.vmware.com/v1alpha1
kind: IPAddressAllocation
metadata:
  name: test-ipv6-default-prefix
  namespace: test-ipv6-ns
spec:
  ipAddressType: IPv6

Result: ALLOCATIONIPS=2001:db8:0:1::/64. Builder defaulted to 64 when field was omitted; NSX allocated the next /64 from the block.

-> Deny: IPv6 + ipAddressBlockVisibility (CEL validation)

apiVersion: crd.nsx.vmware.com/v1alpha1
kind: IPAddressAllocation
metadata:
  name: test-invalid-ipv6-visibility
  namespace: test-ipv6-ns
spec:
  ipAddressType: IPv6
  ipv6AllocationPrefixLength: 64
  ipAddressBlockVisibility: Private

Result: API server rejected with ipAddressBlockVisibility cannot be set when ipAddressType is IPv6. No NSX call made.

-> Deny: IPv6 + allocationSize (CEL validation)

apiVersion: crd.nsx.vmware.com/v1alpha1
kind: IPAddressAllocation
metadata:
  name: test-invalid-ipv6-size
  namespace: test-ipv6-ns
spec:
  ipAddressType: IPv6
  allocationSize: 16

Result: API server rejected with allocationSize can only be set when ipAddressType is IPv4.

-> Deny: allocationSize + allocationIPs together (CEL validation)

apiVersion: crd.nsx.vmware.com/v1alpha1
kind: IPAddressAllocation
metadata:
  name: test-both-invalid
  namespace: test-ipv6-ns
spec:
  ipAddressType: IPv4
  allocationSize: 16
  allocationIPs: "10.0.0.0/28"

Result: API server rejected with Only one of allocationSize or allocationIPs can be specified.

-> Deny: ipAddressType immutability

# Create with IPv4 then attempt patch to IPv6
kubectl patch ipaddressallocation test-immutable -n test-ipv6-ns \
  --type=merge -p '{"spec":{"ipAddressType":"IPv6"}}'

Result: Rejected with spec.ipAddressType: Invalid value: "IPv6": Value is immutable.

[dantingl]

Can one of the admins verify this patch?