Support for Windows Server Core for Containers

Making konlet support Windows Server Core for Containers (and installing it by default) would greatly improve the GCE user experience for deploying Windows containers. It is currently not intuitive that the container feature advertised in the UI only works for (some) linux images. The [best GCP guide](https://codelabs.developers.google.com/codelabs/cloud-windows-containers-computeengine/#0) for deploying containers on Windows currently requires RDP and manual docker commands which is not ideal. If this isn't a feature you are likely to implement then I might be able to make a PR for it with some guidance.

No files or tests are identified in the issue. Start by examining konlet's existing container support and the linked GCP Windows containers guide, then determine the requirements for Windows Server Core and default installation; done means Windows Server Core containers work through the advertised GCE container feature without RDP or manual Docker commands.

Written by the indexing model from the issue text.