Better representing CLI version and dependencies in EKS-A cluster

[jiayiwang7]

The relationship between an EKS-A release and its corresponding bundle is not clear. Furthermore, it is difficult to tell what version of EKS-A was used to create/upgrade a cluster. For these reasons, the bundlesRef field of a cluster should be deprecated in favor of an eksaVersion field. The eksaVersion field should map to an EKSARelease resource on the cluster, which can contain a reference of the release's corresponding bundle.

[tatlat]

Implemented in #6262 and #6268