Add Windows docker file
We should run our Windows CI inside docker just like Linux jobs.
- Currently the CI is run in a shell on the Windows host. Meaning anyone can do anything on the host machines.
- It's not self-contained, a bad MR could screw the env and make other jobs fail.
- The build env is not easily reproducible, with docker we have a Dockerfile that describe exactly how to setup the env.
- Using docker could potentially allow us to more easily move the scalable hosting like AWS.
Edited by Philip Withnall