[feat] add fields for supporting configurable VPC IPv4 prefixes

[AshleyDumaine]

What this PR does / why we need it: This makes use of the new configurable VPC IPv4 Prefix feature in linodego: linode/linodego@7cbc513

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

Special notes for your reviewer:

TODOs:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

[codecov]

Codecov Report

❌ Patch coverage is 82.60870% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.68%. Comparing base (939e91a) to head (a0f4187).

Files with missing lines	Patch %	Lines
...nternal/controller/linodevpc_controller_helpers.go	82.60%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1093      +/-   ##
==========================================
+ Coverage   69.64%   69.68%   +0.03%     
==========================================
  Files          71       71              
  Lines        6579     6600      +21     
==========================================
+ Hits         4582     4599      +17     
- Misses       1708     1710       +2     
- Partials      289      291       +2     

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[Copilot]

Pull request overview

This PR extends CAPL’s LinodeVPC support to expose and reconcile Linode’s configurable VPC IPv4 prefix feature (via linodego), including API/CRD surface area, controller reconciliation behavior, and generated client/test artifacts.

Changes:

• Add spec.ipv4 (allocated) and spec.ipv4Range (requested) fields to LinodeVPCSpec, plus corresponding CRD + reference docs output.
• Plumb linodego VPC IPv4 prefix configuration through VPC create and (for existing VPCs) update reconciliation paths.
• Update Linode client interfaces/wrappers/mocks and adjust/add unit tests for the new behavior.

Reviewed changes

Copilot reviewed 7 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
observability/wrappers/linodeclient/linodeclient.gen.go	Adds tracing wrapper method for UpdateVPC.
mock/client.go	Extends gomock clients with UpdateVPC to match updated interfaces.
internal/controller/linodevpc_controller_test.go	Adds reconciliation coverage expecting UpdateVPC when spec.ipv4Range is set.
internal/controller/linodevpc_controller_helpers.go	Implements IPv4 prefix create options and adds existing-VPC update path + spec field syncing.
internal/controller/linodevpc_controller_helpers_test.go	Updates create-config unit tests to include BYO IPv4 prefix behavior.
docs/src/reference/out.md	Regenerates reference docs to include new LinodeVPC IPv4 fields.
config/crd/bases/infrastructure.cluster.x-k8s.io_linodevpcs.yaml	Extends CRD schema with spec.ipv4 and spec.ipv4Range.
clients/clients.go	Adds UpdateVPC to LinodeVPCClient interface.
api/v1alpha2/zz_generated.deepcopy.go	Regenerates deepcopy implementations for new spec fields/types.
api/v1alpha2/linodevpc_types.go	Adds new LinodeVPCSpec fields and introduces VPCCreateOptionsIPv4 type.

Files not reviewed (3)

• api/v1alpha2/zz_generated.deepcopy.go: Generated file
• mock/client.go: Generated file
• observability/wrappers/linodeclient/linodeclient.gen.go: Generated file

The base branch was changed.

[AshleyDumaine]

Side note for v1beta1: We should rename these controller-set fields so they're less confusing vs IPvXRange.