Add property "windows" to indicate that a CSI driver supports Windows

Using a CSI driver on Windows requires the driver to either use CSI Proxy for privileged operations to be executed on Windows or to not require privileged operations. Either way, there needs to be taken special care to make a CSI driver work on Windows.

For that reason a property called "windows" should be added to reflect if a CSI driver is able to work under Windows-based Kubernetes hosts.