Update WindowsBuild.md
- Sort the arguments to CMake to make them easier to spot
- Sort the clones to be in order of use
- Use shorter build directory names as the paths can be troublesome
- Update instructions all the way through to swift-package-manager as that now works
- Fix instructions for cloning swift-llbuild (the repository contains symlinks)
- Add instructions for new swift-package-manager dependencies
- Homogenise the build rules (they are at this point, largely copy-paste from each one, just listing dependencies)
- Switch `swift-llbuild` to use `clang-cl` instead of `cl` and add a workaround for code splitting
