Add fixed native DNS Client completion probe and acceptance fixture

scripts/DnsClientProbeWorker.ps1

@@ -0,0 +1,15 @@
+param([Parameter(Mandatory)][string]$Resolver,[Parameter(Mandatory)][string]$QueryName)
+$ErrorActionPreference='Stop';$script:ScriptRoot=Split-Path $PSScriptRoot -Parent
+[Console]::OutputEncoding=[Text.UTF8Encoding]::new($false)
+. (Join-Path $PSScriptRoot 'WefArrival.ps1')
+. (Join-Path $PSScriptRoot 'ChannelRead.ps1')
+. (Join-Path $PSScriptRoot 'DnsClientProbe.ps1')
+Initialize-WelaDnsClientProbeNative
+if((Get-Service Dnscache -ErrorAction Stop).Status -ne 'Running'){throw 'DNS Client must already be running.'}
+$before=Get-WelaChannelReader
+$start=[DateTime]::UtcNow.ToString('o')
+$query=[Wela.DnsClientProbe.Native]::Query($QueryName,$Resolver)
+$end=[DateTime]::UtcNow.ToString('o')
+$after=Get-WelaChannelReader
+if((Get-WelaChannelReadKey $before) -cne (Get-WelaChannelReadKey $after)){throw 'Worker primary token changed during DNS query.'}
+[pscustomobject]@{Query=$query;StartedUtc=$start;CompletedUtc=$end;ProcessId=$PID;BeforeToken=$before;AfterToken=$after}|ConvertTo-Json -Depth 12 -Compress