Feature request: support IPv6 pools with Amazon-owned CIDRs

[artem-collectai]

Currently the following doesn't work because top_cidr is required, but conflicts with netmask_length:

module "this6" {
  source  = "registry.terraform.io/aws-ia/ipam/aws"
  version = "~> 2.0.0"

  top_netmask_length = 48

  # scope ID created by another instantiation of this module for an IPv4 pool
  ipam_scope_id   = module.this.ipam_info.public_default_scope_id
  ipam_scope_type = "public"

  create_ipam = false

  top_name       = "global ipam 6"
  address_family = "ipv6"

  pool_configurations = {
    corporate-eu6 = {
      locale = "eu-central-1"
      aws_service = "ec2"

      sub_pools = {
        sandbox = {
          name                 = "sandbox-dev-6"
          netmask_length       = 52
        }
      }
    }
  }
}

[drewmullen]

Thanks for opening this feature request. I will definitely consider how to implement this