Backend: Implement Google Cloud Compute client and services

1. Implement a GoogleCloudPlatform::Compute::Client client, based on the google-cloud-compute gem. This is similar to what was done in !142289 (merged) for the Artifact Registry client.

This client should expose the following methods:

• regions: https://cloud.google.com/ruby/docs/reference/google-cloud-compute/latest/Google-Cloud-Compute#Google__Cloud__Compute_regions_class_
• zones: https://cloud.google.com/ruby/docs/reference/google-cloud-compute/latest/Google-Cloud-Compute#Google__Cloud__Compute_zones_class_
• machineTypes filterable by zones: https://cloud.google.com/ruby/docs/reference/google-cloud-compute/latest/Google-Cloud-Compute#Google__Cloud__Compute_machine_types_class_

2. Implement 3 services leveraging GoogleCloudPlatform::Compute::Client:

• GoogleCloudPlatform::Compute::ListRegionsService

• GoogleCloudPlatform::Compute::ListZonesService

• GoogleCloudPlatform::Compute::ListMachineTypesService

  These services should return hashes representing the data returned by the client. They should also support pagination.