Support g4ad instances (AMD GPUs)

[deliahu]

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Implementation notes

• It will require installing the AMD GPU device plugin.
• The user will need specify that they are requesting AMD gpus (e.g. gpu_amd in the compute configuration)
• Is it a problem that the handler base images are FROM nvidia/cuda?
• Additional changes would be necessary to support the GPU info on the dashboards (can be a separate ticket)