Merge KEP-5339 (ClusterProfile Plugin Credentials) into KEP-4322 (ClusterProfile API)

[mikeshng]

Enhancement Description

• One-line enhancement description (can be used as a release note): Merge KEP-5339 into KEP-4322 so both are tracked as a single enhancement
• Kubernetes Enhancement Proposal: https://github.com/kubernetes/enhancements/tree/master/keps/sig-multicluster/4322-cluster-inventory
• Discussion Link: Combine KEP-5339 and KEP-4332 kubernetes-sigs/cluster-inventory-api#58

KEP-5339 introduced a field (accessProviders) and credential provider plugin mechanism to the ClusterProfile API already established in KEP-4322. Since the base API and the credentials related fields are expected to graduate together to beta/GA, tracking them separately in enhancements is unnecessary.

[mikeshng]

/assign @mikeshng

[mikeshng]

/sig multicluster