Update dependencies from https://github.com/dotnet/arcade build 20200219.14 (#6486)

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.20119.14

eng/common/post-build/check-channel-consistency.ps1

@@ -0,0 +1,25 @@
+param(
+  [Parameter(Mandatory=$true)][string] $PromoteToChannels,            # List of channels that the build should be promoted to
+  [Parameter(Mandatory=$true)][array] $AvailableChannelIds            # List of channel IDs available in the YAML implementation
+)
+
+try {
+  . $PSScriptRoot\post-build-utils.ps1
+
+  # Check that every channel that Maestro told to promote the build to 
+  # is available in YAML
+  $PromoteToChannelsIds = $PromoteToChannels -split "\D" | Where-Object { $_ }
+
+  foreach ($id in $PromoteToChannelsIds) {
+    if (($id -ne 0) -and ($id -notin $AvailableChannelIds)) {
+      Write-PipelineTaskError -Type 'warning' -Message "Channel $id is not present in the post-build YAML configuration!"
+    }
+  }
+
+  Write-Host 'done.'
+} 
+catch {
+  Write-Host $_
+  Write-PipelineTelemetryError -Category 'CheckChannelConsistency' -Message "There was an error while trying to check consistency of Maestro default channels for the build and post-build YAML configuration."
+  ExitWithExitCode 1
+}