feat(lxc): add container datasource

[h3krn]

Contributor's Note

• I have added / updated documentation in /docs for any user-facing features or additions.
• I have added / updated acceptance tests in /fwprovider/tests for any new or updated resources / data sources.
• I have ran make example to verify that the change works as expected.

Proof of Work

$ cat datasource.tf 
data "proxmox_virtual_environment_container" "test" {
  vm_id = "133"
  node_name    = "pve-host"
}

output "ip_address" {
  value = data.proxmox_virtual_environment_container.test
}
$ tofu apply
╷
│ Warning: Provider development overrides are in effect
│ 
│ The following provider development overrides are set in the CLI configuration:
│  - bpg/proxmox in /home/harm/go/bin
│ 
│ The behavior may therefore not match any released version of the provider and applying changes may cause the state to become incompatible with published releases.
╵
data.proxmox_virtual_environment_container.test: Reading...
data.proxmox_virtual_environment_container.test: Read complete after 0s [id=133]

Changes to Outputs:
  + ip_address = {
      + id        = "133"
      + name      = "k3s-controller-02"
      + node_name = "pve-host"
      + status    = "running"
      + tags      = [
          + "k3s_cluster",
          + "master",
        ]
      + template  = false
      + vm_id     = 133
    }

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Closes #965

[bpg]

Hey @h3krn 👋🏼

Thanks for adding this feature! Let me know if you need a hand to finish it.

[h3krn]

Hi @bpg,

Thanks, while I do know some programming (mainly python, bash and some perl and C from the old days)
I'm really new to golang. So have a lot to learn and my PR's won't be rocket science.

Technically the PR as is works, but I'm trying to find out what it would take to clear the linter warning. The vm and lxc API endpoints seem fairly similar, but I'll try to figure out if they are actually identical and if it's worth to parametrize this and avoid duplication (without shooting myself in the foot).
If this is not the case, would it be acceptable to silence this specific linter warning?