Make disabling and enabling RDP more robust
Enhance the DisableRemoteDesktopConnections task, so disabling and re-enabling RDP is more robust, and respects Image-specific policy. Previously, snf-image would disable RDP unconditionally inside DisableRemoteDesktopConnections and assume there would be an appropriate <RunSynchronousCommand> entry in unattend.xml so SYSPREP would enable RDP unconditionally during the specialize pass of the Windows Setup. This has two main problems: * It assumes a specific answer file, with snf-image specific content. However, the answer file is Image-specific policy, and ideally snf-image should not make any assumption on its contents. * It enables RDP unconditionally, even though it may have been disabled inside a specific Image by the Administrator, on purpose, thus introducing a potential security risk. To solve this problem, make DisableRemoteDesktopConnections self-standing: * Note whether RDP was initially disabled or not, * Disable it unconditionally via a direct edit of the Registry, so no incoming RDP connections are allowed while SYSPREP is running, * Insert a command to set it to its original state when Setup is complete, without depending on the contents of unattend.xml or other answer file.