Support AWS ECR OCI Download [SURE-8875]

[manno]

The request is to support AWS ECR (Elastic Container Registry) authentication in Rancher Fleet. Currently, Rancher Fleet supports user-password and SSH key methods for Helm chart repositories but lacks native support for AWS-specific authentication mechanisms.

Assume https://external-secrets.io/latest/api/generator/ecr/ is used to generate a secret with the token and refresh it.

Rancher Fleet should support using that token to access and manage Helm charts stored in AWS ECR.

• Do tokens work with fleet?
• Is ESO or Rancher ECR Credential Updater in the Rancher marketplace?