Make CI more robust
VTK-m's Windows CI currently relies on ninja and CMake already existing on the machine. This makes machine maintenance and upkeep far harder. VTK-m should instead download these tools during the CI process. This ensures that (at least):
- machines do not need to be set up with every version ever expected by VTK-m
- updates can occur without updating N machines
- visibility and editability into the full CI setup by developers