feature: configure federated learning service accounts

[ferrarimarco]

• Define a variable to define tenants.
• Define tenants local variables. For each tenant, define:
  • Name
  • Name of the node pool (will be used in the future)
  • Node pool service account name
  • workloads service account name
  • Kubernetes service account name (will be used in the future)
• Ensure that the IAM API is enabled
• Create the Google Cloud service accounts
• Order resource attributes alphabetically

On the core platform side:

• Fix a few quoting issues in scripts
• Parse CORE_TERRASERVICES_APPLY and CORE_TERRASERVICES_DESTROY to build arrays so we don't need to source core platform scripts to use them.