Add VGPU_type <-> VGPUs relation

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Expose VGPU_type.VGPUs on the CLI

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Merge pull request #1411 from simonjbeaumont/vgpu-cli-improvements

Add VGPU_type <-> VGPUs relation to datamodel