Support for EKS Hybrid Node bootstrap generation

/kind feature

Describe the solution you'd like Add support for generating bootstrap configuration (and credentials) for CAPI managed nodes to join an EKS cluster using the Hybrid Node feature.

Anything else you would like to add: EKS has support for enabling non-EC2 instances to join an EKS cluster as Nodes using the Hybrid Node feature. This process involves enabling some configuration on the control-plane itself, as well as generating credentials for the Machine to use when executing the nodeadm bootstrapper.

Supporting this feature provides a path for cluster-api providers to be used to create a CAPI-managed hybrid cluster using EKS across multiple providers.

This feature would leverage the work laid out in https://github.com/kubernetes-sigs/cluster-api-provider-aws/pull/5700, ideally extending the NodeadmConfig CRD to support additional parameters to support the creation of short-lived SSM activation on-demand as part of the Machine Bootstrap generation.

I am keen to contribute this feature if there is appetite to extend CAPA to support it.

Environment:

• Cluster-api-provider-aws version: n/a
• Kubernetes version: (use kubectl version): 1.32+
• OS (e.g. from /etc/os-release): All