Fix windows chown to work with single file (#51004)

The chown utility for packaging tests works on windows when the given
path is a directory, but would fail if the path was a single file. This
commit fixes it to handle both cases.

relates #50825

Author: rjernst

qa/os/src/test/java/org/elasticsearch/packaging/util/Shell.java

@@ -88,9 +88,13 @@ public void chown(Path path) throws Exception {
         Platforms.onLinux(() -> run("chown -R elasticsearch:elasticsearch " + path));
         Platforms.onWindows(() -> run(
             "$account = New-Object System.Security.Principal.NTAccount '" + System.getenv("username")  + "'; " +
-                "$tempConf = Get-ChildItem '" + path + "' -Recurse; " +
-                "$tempConf += Get-Item '" + path + "'; " +
-                "$tempConf | ForEach-Object { " +
+                "$pathInfo = Get-Item '" + path + "'; " +
+                "$toChown = @(); " +
+                "if ($pathInfo.PSIsContainer) { " +
+                "  $toChown += Get-ChildItem '" + path + "' -Recurse; " +
+                "}" +
+                "$toChown += $pathInfo; " +
+                "$toChown | ForEach-Object { " +
                 "$acl = Get-Acl $_.FullName; " +
                 "$acl.SetOwner($account); " +
                 "Set-Acl $_.FullName $acl " +