* Enabling building ML.NET for .NET Core 3.0 in the official builds.
* Update .sln for the new configuration
* Fix native build on windows.
* Fix netfx configuration by working around an sdk bug.
* Fix CpuMath tests on netfx.
Combine the two separate CpuMath UnitTest projects into a single project.
* Install the .NET Core 2.1 runtime so we can execute tests against it.
* Remove crossgen call since the crossgen executable is no longer shipped in the NuGet package.
We don't need many things from the Tools directory, so removing crossgen won't affect build performance very much.
* Move to netcoreapp2.1
* PR Feedback
* Fix F# test to build with latest tools
* Fix up a couple more netcoreapp2.0 usages
* Update baselines to work around .NET Core 2.1 change
See https://github.com/dotnet/corefx/issues/31847
* Bump the CLI version to 401.
Add a comment to F# test project.