[Feature Request] Skip Kubernetes install

[chivalryq]

For users who have K8s already, VelaD can provide a --skip-cluster param so that VelaD can be used as offline KubeVela install toolkit.

[ArenaSu]

It's good !

[wonderflow]

How to load the image in this case?

[chivalryq]

We've talked about this problem. For now, I haven't come up with an idea. With kubeconfig only, it's impossible to load images.

[chivalryq]

@ArenaSu came up with an idea.

1. Add --skip-cluster and param like --registry, so that all vela images will be pushed in this image registry.
2. Replace all image prefix in vela-core helm chart.

Note that --skip--cluster must came with --registry, or throw an error.

[chivalryq]

Maybe we should split this into two commands.

1. push-images will push vela-core and VelaUX images to image registry, which save time for docker pull and docker push.
2. install accept --skip-cluster and --registry. When passing --registry, all vela image registry will be replaced.

[wonderflow]

I don't think this is a necessary work by now.