Added blue/green deployment block to Aurora (WIP)

[autotune]

Adds an option for blue/green deployments to RDS MySQL Aurora.

resource "aws_rds_cluster" "default" {

 blue_green_update { 
    enabled =  false 
 }
  cluster_identifier = "aurora-cluster-demo-old"
  availability_zones = ["us-east-1b", "us-east-1c", "us-east-1d"]
  database_name      = "mydb"
  master_username    = "foo"
  master_password    = "barbut8chars"
  engine             = "aurora-mysql"
  skip_final_snapshot = true
  db_cluster_parameter_group_name = "green"
}

resource "aws_rds_cluster_instance" "cluster_instances" {
  depends_on         = [aws_rds_cluster.default]
  count              = 2 
  identifier         = "aurora-cluster-demo-${count.index}"
  cluster_identifier = aws_rds_cluster.default.id
  engine             = aws_rds_cluster.default.engine
  engine_version     = aws_rds_cluster.default.engine_version
  instance_class     = "db.x2g.large"
  db_parameter_group_name = "logicalreplication2"
}

Change to true after resources are created.

Relations

Closes #28956

Output from Acceptance Testing

There is no acceptance testing for the original code. This requires existing resources already in place I'm not sure it's possible to create tests for this.

[github-actions]

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[autotune]

I'm closing this in favor of #33978, which turns this into its own resource that tests can be implemented for.

[github-actions]

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