Accelerate local builds in Visual Studio (#3026)

* Accelerate builds of SDK-style .NET projects https://github.com/dotnet/project-system/blob/main/docs/build-acceleration.md#validate-builds-are-accelerated

* Verbose logging produced "Ensure projects producing the following outputs have the 'ProduceReferenceAssembly' MSBuild property set to 'true': 'D:\GitWorkspace\ILSpy\ICSharpCode.Decompiler\bin\Debug\netstandard2.0\ICSharpCode.Decompiler.dll'" - this relates to the documented problem of netstandard2.0 projects not generating the necessary reference assemblies (direct issue link dotnet/project-system#8865) No harm for netcore projects as these produce those ref asms by default.

Directory.Build.props

@@ -0,0 +1,6 @@
+<Project>
+  <PropertyGroup>
+    <AccelerateBuildsInVisualStudio>true</AccelerateBuildsInVisualStudio>
+    <ProduceReferenceAssembly>true</ProduceReferenceAssembly>
+  </PropertyGroup>
+</Project>