dashboard: add configs for new windows 2008, 2012, 2016 builders

See also: https://golang.org/cl/41142

Updates golang/go#17513

Change-Id: Ie743ae4604e65892e28423ed0af008450b647197
Reviewed-on: https://go-review.googlesource.com/41393
Reviewed-by: Jeff Johnson <jrjohnson@google.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
4 files changed