Add energy billing consumer module for budget plan events (#1173)

This pull request adds a new module to provision TLS credentials for the
`energy_billing_consumer` application, enabling it to securely consume
messages from the `property_migration_events` Kafka topic.

**Infrastructure additions:**

* Added a new `energy_billing_consumer` module using the `tls-app`
module to provision TLS certificates and configure it to consume from
the `property_migration_events` Kafka topic with the
`energy-billing.budget-plan-events-consumer` group.

Author: agkountis

prod-aws/kafka-shared-msk/energy-platform/properties.tf

@@ -23,3 +23,10 @@ module "gentrack_migration_worker" {
   produce_topics   = [kafka_topic.property_migration_events.name]
   cert_common_name = "energy-platform/gentrack-migration-worker"
 }
+
+module "energy_billing_consumer" {
+  source           = "../../../modules/tls-app"
+  consume_topics   = [kafka_topic.property_migration_events.name]
+  consume_groups   = ["energy-billing.budget-plan-events-consumer"]
+  cert_common_name = "energy-billing/budget-plan-events-consumer"
+}