Add Proxmox VE infrastructure provider support using Ansible (feat)

[aliharirian]

What would you like to be added

Add Proxmox VE as an infrastructure provider in Kubespray under contrib/proxmox/.

This includes:

• Ansible playbook to provision VMs on Proxmox VE using ansible or terraform module
• Cloud-init support for VM initialization (user, SSH key, IP configuration)
• Auto-generate Kubespray inventory file after VMs are provisioned
• Documentation and usage example

This follows the same pattern as the existing vSphere implementation
and does not require Terraform.

Why is this needed

Proxmox VE is a widely used open-source virtualization platform,
especially in on-premise and homelab environments.

Currently, Kubespray does not support Proxmox VE as an infrastructure
provider. Users have to manually create and configure VMs before running
Kubespray, which is time-consuming and error-prone.

Adding Proxmox VE support would:

• Automate the VM provisioning step for Proxmox users
• Make Kubespray more accessible for on-premise environments
• Align with existing provider support like vSphere and OpenStack

[aliharirian]

I am willing to implement this feature and submit a PR.

[tico88612]

We don't have much bandwidth for the contrib/ directory. Furthermore, since we aren't running CI on Proxmox VE, we lack the motivation to maintain it.