Get a multi-region scaletest cluster & Coder deployment up using Terraform

[spikecurtis]

Using https://github.com/coder/coder/tree/main/scaletest/terraform/action get a small multi-region cluster up and running.

• choose GCP project and gather required credentials
• ensure credentials are stored in 1Password
• document internally how to set things up and where to find credentials

Not in scope:

• running any automated tests -- just manually confirm cluster is operable
• ensuring telemetry is flowing