Changes:

* Make Visual Studio 2019 a prerequisite for building this repo
* Update .sln files
* Update Windows SDK to 17134
* Update developer docs
* Disable ANCM tests
* Update to .NET Core SDK 3.0 Preview 2
* Use Microsoft.NET.Sdk.Razor as a package consistently accross the repo
* React to changes in metadata from Microsoft.NETCore.App
* React to changes in .NET Core SDK
* Attempt to workaround CodeCheck.ps1 failure which doesn't repro locally or on different agents. Possibly due to differences in the version of the PowerShell task?
* Remove dead YML file
* Rename usages of win7-{x64,x86} to win-{x64,x86}
* Update KoreBuild to 3.0.0-build-20190219.1