Windows ProductKey cleanup

Minor fixup for the location of Windows Product Key in the Autounattended.xml

The product key needs to be in a subkey of 'Key' in the 'ProductKey' XML element - so for the one file with an actual key I have done this.

For the others, I have moved the element order into alphabetical order - this makes it easier to diff them against one-another and if the order is maintained, across versions.

Finally the batch file for install-vbox.bat fails due to '#' markers which are not comments in Windows.