Follow established Terraform patterns for panel-exchange-client

[SanjayVas]

After the panel-exchange-client repo merge, the panel-exchange-client Terraform configs live under src/main/terraform/panel-match. They should be merged into the current repo structure under src/main/terraform/gcloud or src/main/terraform/aws. Modules go under the modules subdirectory of each of those respective paths.

In addition, the panel-exchange-client Terraform configurations should be updated to follow the same principles/patterns:

• Terraform modules should be configurable for any environment.
  • This means machine types, project names, etc. should be specified via configuration variables.
• Terraform is only used to manage cloud project infrastructure, not Kubernetes objects
  • The one exception is for Kubernetes service accounts due to the tight coupling with cloud IAM. See the corresponding documentation for Google Cloud and AWS
• Terraform configurations can be applied without using Bazel to build anything.