Add a job for testing windows in GCE
Add a job for testing windows in GCE

This job currently uses a non-upstream kubernetes repository as a
prototype.

GoogleCloudPlatform/testgrid,GoogleCloudPlatform/testgrid,GoogleCloudPlatform/testgrid,GoogleCloudPlatform/testgrid,GoogleCloudPlatform/testgrid,GoogleCloudPlatform/testgrid