add better support for nvidia gpus

[kkoshelev]

This makes GoW more compatible with vGPU configuration.

1. vGPU requires drivers to be manually installed from specific xxx.run package provided by nVidia. Added logic to detect whether nVidia drivers are present in the different location for Ubuntu.
2. VMs with vGPU typically have two VGA adapters. For this case make sure that xorg uses nVidia GPU as primary.