I've created a new Rancher 2.7.0 cluster with RKE2 on our air-gap environment. Now I need to install istio on it. I assume default https://git.rancher.io/partner-charts contain all necessary charts for it, but repo is not accessible directly. How I could download all necessary charts and images to have it on my personal repository? Or maybe some one had same challenges with air gaped env, will be appreciate for any help.