Add Service Responders to Terraform Modules

[yvzaclohrenz]

Expected Behavior

Opsgenie Service should have parity to the Web GUI in that you should be able to define the responder/audience assigned to the service.
This is important in a Terraform shop where users provision their services via Terraform, this limitation makes Opsgenie a non-starter since you must use the GUI to define the responder.

Actual Behavior

This is not supported at all, currently: https://registry.terraform.io/providers/opsgenie/opsgenie/latest/docs/resources/service
It's supported via API workaround: https://docs.opsgenie.com/docs/service-audience-template-api

References

This would resolve open FR https://jira.atlassian.com/browse/OPSGENIE-85