Add cmdlet Copy-VNOSCustomizationSpec to support copy OSCS to different vCenter

[mtboren]

Rather than someone having to GUI -> export -> GUI -> import to copy an OSCS from one vCenter to another, how about a function that will do this? Expected usage would be like:

Get-OSCustomizationSpec -Name myOSCS -Server mySourceVC | Copy-VNOSCustomizationSpec -DestinationVCenter myDestVC

[mtboren]

Would boil down to a core of:

$viewCustSpecMgr_targetvc.CreateCustomizationSpec($viewCustSpecMgr_targetvc.XmlToCustomizationSpecItem($viewCustSpecMgr_sourcevc.CustomizationSpecItemToXml($oSourceOscs.ExtensionData)))

Then, user might just need to set the Admin password in that new OSCS.