feat(nodeclass): add agentList to enable OCI agent plugins on launched instances

[p2pdkivenko]

Description

Adds a new agentList field to OCINodeClassSpec so users can enable Oracle Cloud Agent plugins (Bastion, Block Volume Management, Compute Instance Monitoring, OS Management Service Agent, etc.) on Karpenter-launched instances without having to ship custom cloud-init.

Each entry in the list is forwarded to LaunchInstanceDetails.AgentConfig.PluginsConfig with DesiredState=ENABLED. When the field is empty or unset, AgentConfig stays nil and behavior is unchanged from today (image defaults apply). The same shape is already used by the sibling project zoom/karpenter-oci, so existing user manifests transfer over directly.

Example:

apiVersion: oci.oraclecloud.com/v1beta1
kind: OCINodeClass
metadata:
  name: example
spec:
  # ...existing fields...
  agentList:
    - Bastion
    - Block Volume Management

Fixes #22

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• New unit test TestProvider_BuildAgentConfig in pkg/providers/instance/provider_test.go covering nil, empty, single-plugin, and multi-plugin cases.

• Existing instance provider test suite (go test ./pkg/providers/instance/...) passes locally.

• make gogen regenerates CRD YAML and zz_generated.deepcopy.go cleanly; both regenerated artifacts are included in the diff.

• go build ./... succeeds for all packages touched by this change. (The pre-existing test/e2e/utils.go: undefined: NodePoolLabel build failure on main is unrelated to this change.)

• Kubernetes version: 1.30

• OKE version: n/a (provider built locally)

• Karpenter Provider OCI version: built from this branch

• Installation method: local run (go test)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas (godoc on the new agentList field documenting accepted plugin names and ENABLED-only semantics)
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[oracle-contributor-agreement]

Thank you for your pull request and welcome to our community! To contribute, please sign the Oracle Contributor Agreement (OCA).
The following contributors of this PR have not signed the OCA:

• PR author: daniil.kivenko@p2p.org (@p2pdkivenko)

To sign the OCA, please create an Oracle account and sign the OCA in Oracle's Contributor Agreement Application.

When signing the OCA, please provide your GitHub username. After signing the OCA and getting an OCA approval from Oracle, this PR will be automatically updated.

If you are an Oracle employee, please make sure that you are a member of the main Oracle GitHub organization, and your membership in this organization is public.

[oracle-contributor-agreement]

Thank you for signing the OCA.

[arindam-bandyopadhyay]

Please run make verify and fix the findings, please squash the commits to a single commit. Also, make your changes on top of the current main

[arindam-bandyopadhyay]

LGTM