Enhance namespace handling, update GCS service account script, minor fixes to other provided script examples

[drpotters]

Proposed changes

This pull request updates the GCP onboarding documentation and improves the Terraform configuration for F5 XC namespaces. The most important changes are grouped below by theme.

GCP Documentation Improvements:

• Enhanced the setup instructions in docs/ADSP-UC1-GCP.md to:
  • Use parameterized variables for service account and pool names, and add explicit steps for creating and granting roles to the service account.
  • Add an attribute condition to the Workload Identity Provider to restrict access to a specific GitHub organization.
  • Use gcloud storage cat instead of gsutil cat for retrieving state files, and combine related outputs (e.g., BIG-IP IP and password, internal IPs) into single commands for clarity. [1] [2]
  • Correct the BIG-IP GUI port in usage instructions from 443 to 8443.

Terraform Namespace Handling:

• Updated f5/xc/namespace.tf to:
  • Add logic for detecting and using an existing Volterra namespace, or creating one if it does not exist, via a new null_resource and data source. This prevents unnecessary resource creation and state changes.
  • Add the null provider to f5/xc/versions.tf to support the new resource logic.

[knowbase]

Move the data resource into data.tf