Use VS2019 Preview for libraries build which contains a newer CMake

[safern]

Fixes: #31888

This re-enable warnaserror on Windows as it was before.

The reason why I just updated it for Libraries is because coreclr was failing because of the newer Windows SDK when building the tests. It seems like the toolset changed so I’ll follow up with @MattGal and when I’m back update to use the same pool and toolset for the whole repo. Also because of that I can’t enable warnaserror in the live local CI build but we get enough coverage with the regular CI build with this change now.

cc: @dotnet/runtime-infrastructure @stephentoub

[MattGal]

LGTM. I like the idea of leaving it around as a switch so you can turn it off and on. I almost wonder if you should add the switch to coreclr and start it as off?

[stephentoub]

Thanks for getting us back to a good state, @safern (or, at least a better one).

[safern]

Perf job is failing. Need to take a look at what’s going on and I’ll update the PR before merging.