[master] Update dependencies from mono/linker Microsoft/vstest (#36692)
* Update dependencies from https://github.com/mono/linker build
20200518.5
Microsoft.NET.ILLink.Tasks
From Version 5.0.0-preview.3.20268.2 -> To Version 5.0.0-preview.3.20268.5
* Update dependencies from https://github.com/microsoft/vstest build
20200518-01
Microsoft.NET.Test.Sdk
From Version 16.7.0-preview-
20200515-03 -> To Version 16.7.0-preview-
20200518-01
Co-authored-by: dotnet-maestro[bot] <dotnet-maestro[bot]@users.noreply.github.com>