/kind feature

Describe the solution you'd like
As a user I'd like to declarative define which GPU I want for my instances

Anything else you would like to add:
https://cloud.google.com/compute/docs/gpus/add-gpus#create-gpu-instance-api

We'd need to expose this in the machineInfra API and do the plumbing with GCP API through:

// GuestAccelerators: A list of the type and count of accelerator cards
// attached to the instance.
GuestAccelerators []*AcceleratorConfig `json:"guestAccelerators,omitempty"`

https://raw.githubusercontent.com/googleapis/google-api-go-client/master/compute/v1/compute-gen.go