1. Proposed title of this feature request

Support for Spot VMs on GCP

2. What is the nature and description of the request?

GCP started offering Spot VM which is a newer version of preemptible VM.

Currently, OpenShift can use the preemptible VM option in MachineSet but does not provide the Spot VM option. 

3. Why does the customer need this? (List the business requirements here)

Preemptible VMs' runtime is restricted to 24 hours, however, Spot VMs do not have this restriction.

GCP offers Spot VMs as the first option, while they continue to support preemptible instances.

https://cloud.google.com/compute/docs/instances/preemptible

4. List any affected packages or components.

machine-api-provider-gcp