device-test.ps1: add verbose flag (#4522)

Author: jpnurmi

scripts/device-test.ps1

@@ -1,3 +1,4 @@
+[CmdletBinding()] # -Verbose
 param(
     [Parameter(Position = 0, Mandatory = $true)]
     [ValidateNotNullOrEmpty()]
@@ -94,6 +95,10 @@ try
         Remove-Item -Recurse -Force test_output -ErrorAction SilentlyContinue
         try
         {
+            if ($VerbosePreference)
+            {
+                $arguments += '-v'
+            }
             xharness $group test $arguments --output-directory=test_output
             if ($LASTEXITCODE -ne 0)
             {