Add new reference packages

[ViktorHofer]

Add new reference projects for the following packages:

Microsoft.Build,17.11.48
Microsoft.Build,17.12.50
Microsoft.Build,17.14.28
Microsoft.Build.Tasks.Core,17.11.48
Microsoft.Build.Tasks.Core,17.12.50
Microsoft.Build.Tasks.Core,17.14.28
Microsoft.Build.Utilities.Core,17.11.48
Microsoft.Build.Utilities.Core,17.12.50
Microsoft.Build.Utilities.Core,17.14.28
Microsoft.Build.Framework,17.11.48
Microsoft.Build.Framework,17.12.50
Microsoft.Build.Framework,17.14.28