feature request: Ability to "inject" images to remote cluster

### Feature Request

Our team is maintaining an open-sourced project, while also providing it as a SaaS product.
So we want our git commit tree to be clean as possible.

We decided to use Skaffold, because it allows us to build images locally and Skaffold applies it to our existing Kubernetes cluster.

We use Skaffold in a so-called *"experimenal"* environment, where developers can test their new codes freely without making a git commit and triggering CI/CD pipeline.

We do not want to add additional operational cost for an image registry to store images for this experimental environment.

So, it would be nice if **Skaffold can "inject" the locally built new image into remote Kubernetes cluster without pushing it to image registry.** I don't know if it will be possible, but there must be some way to implement this.

This feature would be surely amazing!
And I would love to contribute for this new feature, if maintainers decide that it is valuable.