Command line argument encoding is broken on Windows

[alexrp]

See: dotnet/msbuild#6672

Here's where it happened on CI: https://github.com/alexrp/zig-msbuild-sdk/runs/3062030033?check_suite_focus=true#step:9:32

[alexrp]

Note that this becomes less of an issue with #18, but doesn't go away entirely.

[alexrp]

I am no longer able to reproduce the MSBuild bug.