Allow ASG tags to propagate at launch

[joverman-collective]

To help with cost allocation reporting, it would be helpful to have some tags applied to the EC2 instances created by the ASG at launch. It seems here, it's hardcoded to false and only the Name tag is allowed to propagate:

Reference

  dynamic "tag" {
    for_each = var.tags

    content {
      key                 = tag.key
      value               = tag.value
      propagate_at_launch = false
    }
  }

We could perhaps add a new variable such as propagted_tags to allow for both propagated and non-propagated tags to not break existing functionality while allowing for extra propagated tags as well.