Set integer fields as pointers

[karencfv]

I've additionally manually tested by updating the terraform provider locally and running all acceptance tests and with the following terraform config:

terraform {
  required_version = ">= 1.0"

  required_providers {
    oxide = {
      source  = "oxidecomputer/oxide"
      version = "0.8.0-dev"
    }
  }
}

resource "oxide_vpc_firewall_rules" "talos_k8s_nodeports" {
  vpc_id = "8c2757bc-1cea-422c-ba66-e330bfbcaf92"
  rules = [
    {
      name        = "talos-k8s-nodeports"
      description = "Talos Kubernetes node ports."
      action      = "allow"
      direction   = "inbound"
      priority    = 0
      status      = "enabled"
      filters = {
        ports     = ["30000-32767"]
        protocols = ["TCP"]
      },
      targets = [
        {
          type  = "vpc"
          value = "dud"
        }
      ]
    }
  ]
}

$ terraform apply
<...>

Terraform used the selected providers to generate the following execution plan. Resource actions
are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # oxide_vpc_firewall_rules.talos_k8s_nodeports will be created
  + resource "oxide_vpc_firewall_rules" "talos_k8s_nodeports" {
      + id     = (known after apply)
      + rules  = [
          + {
              + action        = "allow"
              + description   = "Talos Kubernetes node ports."
              + direction     = "inbound"
              + filters       = {
                  + ports     = [
                      + "30000-32767",
                    ]
                  + protocols = [
                      + "TCP",
                    ]
                }
              + id            = (known after apply)
              + name          = "talos-k8s-nodeports"
              + priority      = 0
              + status        = "enabled"
              + targets       = [
                  + {
                      + type  = "vpc"
                      + value = "dud"
                    },
                ]
              + time_created  = (known after apply)
              + time_modified = (known after apply)
            },
        ]
      + vpc_id = "8c2757bc-1cea-422c-ba66-e330bfbcaf92"
    }

Plan: 1 to add, 0 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

oxide_vpc_firewall_rules.talos_k8s_nodeports: Creating...
oxide_vpc_firewall_rules.talos_k8s_nodeports: Creation complete after 0s [id=076a749e-7876-45f1-85dc-fd1bf01ea5a8]

Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

Closes: #273 #245 oxidecomputer/terraform-provider-oxide#403

[sudomateo]

Changes look good! Thanks for working on this.