feat: Automatically append .fifo to fifo topic names (#55)

With this change, we automatically append the .fifo suffix to fifo topic names since it is required by AWS SNS.
We also sanitize the name input to ensure that if users have already included the .fifo suffix
in their topic names it will not be appended again.

main.tf

@@ -4,11 +4,15 @@ data "aws_caller_identity" "current" {}
 # Topic
 ################################################################################
 
+locals {
+  name = try(trimsuffix(var.name, ".fifo"), "")
+}
+
 resource "aws_sns_topic" "this" {
   count = var.create ? 1 : 0
 
-  name        = var.use_name_prefix ? null : var.name
-  name_prefix = var.use_name_prefix ? var.name : null
+  name        = var.use_name_prefix ? null : (var.fifo_topic ? "${local.name}.fifo" : local.name)
+  name_prefix = var.use_name_prefix ? "${local.name}-" : null
 
   application_failure_feedback_role_arn    = try(var.application_feedback.failure_role_arn, null)
   application_success_feedback_role_arn    = try(var.application_feedback.success_role_arn, null)