GitHub is apparently in a 4-week migration to switch to Windows Server
2022 instead of Windows Server 2019 for `windows-latest` tags, and we've
been caught in the middle of the transition with a Terraria update.
Rather than trying to update our build scripts to run on 2022, this
temporarily downgrades us to Windows Server 2019 so we can actually
update Terraria and not windows.
This changeset fixes several problems with the github actions build. It
removes the dependency on a repo script to install msbuild + VS. It
switches the shell back to cmd.exe, so that the scripts in build.yml
continue to run. It installs nuget via chocolatey, since that's not on
the path by default. Finally, it also uses built in MSBUILD to satisfy
the first statement.
