Update dependencies from https://github.com/dotnet/arcade build 20190827.8 (#4367)

- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.19427.8

eng/common/sdl/init-sdl.ps1

@@ -11,6 +11,9 @@ $ErrorActionPreference = "Stop"
 Set-StrictMode -Version 2.0
 $LASTEXITCODE = 0
 
+# Don't display the console progress UI - it's a huge perf hit
+$ProgressPreference = 'SilentlyContinue'
+
 # Construct basic auth from AzDO access token; construct URI to the repository's gdn folder stored in that repository; construct location of zip file
 $encodedPat = [Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes(":$AzureDevOpsAccessToken"))
 $escapedRepository = [Uri]::EscapeDataString("/$Repository/$BranchName/.gdn")