[master] Update dependencies from dnceng/internal/dotnet-wpf-int (dotnet/core-setup...

[master] Update dependencies from dnceng/internal/dotnet-wpf-int (dotnet/core-setup#6504)

* Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20190521.7

- Microsoft.DotNet.Wpf.DncEng - 4.8.0-preview6.19271.7

* Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20190522.2

- Microsoft.DotNet.Wpf.DncEng - 4.8.0-preview6.19272.2

Dependency coherency updates

- Microsoft.DotNet.Wpf.GitHub - 4.8.0-preview6.19271.2 (parent: Microsoft.DotNet.Wpf.DncEng)

* Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20190522.4

- Microsoft.DotNet.Wpf.DncEng - 4.8.0-preview6.19272.4

Dependency coherency updates

- Microsoft.DotNet.Wpf.GitHub - 4.8.0-preview6.19271.2 (parent: Microsoft.DotNet.Wpf.DncEng)

* Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20190522.11

- Microsoft.DotNet.Wpf.DncEng - 4.8.0-preview6.19272.11

Dependency coherency updates

- Microsoft.Private.Winforms - 4.8.0-preview6.19266.1 (parent: Microsoft.DotNet.Wpf.DncEng)
- Microsoft.DotNet.Wpf.GitHub - 4.8.0-preview6.19272.6 (parent: Microsoft.DotNet.Wpf.DncEng)

* Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20190523.5

- Microsoft.DotNet.Wpf.DncEng - 4.8.0-preview6.19273.5

Dependency coherency updates

- Microsoft.Private.Winforms - 4.8.0-preview6.19266.1 (parent: Microsoft.DotNet.Wpf.DncEng)
- Microsoft.DotNet.Wpf.GitHub - 4.8.0-preview6.19273.1 (parent: Microsoft.DotNet.Wpf.DncEng)

* Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20190523.6

- Microsoft.DotNet.Wpf.DncEng - 4.8.0-preview6.19273.6

Dependency coherency updates

- Microsoft.Private.Winforms - 4.8.0-preview6.19272.1 (parent: Microsoft.DotNet.Wpf.DncEng)
- Microsoft.DotNet.Wpf.GitHub - 4.8.0-preview6.19273.1 (parent: Microsoft.DotNet.Wpf.DncEng)

* Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20190523.7

- Microsoft.DotNet.Wpf.DncEng - 4.8.0-preview6.19273.7

Dependency coherency updates

- Microsoft.Private.Winforms - 4.8.0-preview6.19272.1 (parent: Microsoft.DotNet.Wpf.DncEng)
- Microsoft.DotNet.Wpf.GitHub - 4.8.0-preview6.19273.1 (parent: Microsoft.DotNet.Wpf.DncEng)

* Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20190524.5

- Microsoft.DotNet.Wpf.DncEng - 4.8.0-preview6.19274.5

Dependency coherency updates

- Microsoft.Private.Winforms - 4.8.0-preview6.19272.1 (parent: Microsoft.DotNet.Wpf.DncEng)
- Microsoft.DotNet.Wpf.GitHub - 4.8.0-preview6.19273.5 (parent: Microsoft.DotNet.Wpf.DncEng)

* Update dependencies from https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-int build 20190524.6

- Microsoft.DotNet.Wpf.DncEng - 4.8.0-preview6.19274.6

Dependency coherency updates

- Microsoft.Private.Winforms - 4.8.0-preview6.19272.1 (parent: Microsoft.DotNet.Wpf.DncEng)
- Microsoft.DotNet.Wpf.GitHub - 4.8.0-preview6.19273.5 (parent: Microsoft.DotNet.Wpf.DncEng)

* Fix WindowsDesktop package validation

The wpf-int change allows NuGet to pick up the native files, including PDBs. This lets us remove a workaround target, but causes some duplicates that must be filtered out due to assumptions the packaging tooling makes.

Commit migrated from https://github.com/dotnet/core-setup/commit/1ac29fa4fed3f5658864593e9b649238f52f3748