Draft: ci: add a runner for Windows 10
This is modeled after the runner in Mercurial 8766d47edfd1, with some of the simplifications present in hg f9f41b3dcb64.
All legacy (hg-git based) Projects have been automatically migrated to native with the upgrade of 2025-01-23
This is modeled after the runner in Mercurial 8766d47edfd1, with some of the simplifications present in hg f9f41b3dcb64.