Windows CI job

Just a few of us use Windows.
We need to assert that our releases work on Windows.
There are some Windows nodes on build.a.o, see https://cwiki.apache.org/confluence/display/INFRA/Jenkins+node+labels

We need to setup a CI check job targetted at Windows nodes to ensure we don't break on this OS.

Given that there are just a few Windows nodes available, a commit job is probably not a good idea, something that runs weekly should help already.