feat: add proxmox widget

[aatumaykin]

Hi.

I am providing my own version of the integration with the proxmox server.

It is possible to display statistics for all nodes in the cluster.

Proxmox API Token To generate an API Token for Proxmox in the Proxmox Web UI go to Datacenter -> Permissions -> API Token -> Add.

After clicking Add the UI shows this.

In the settings you need to specify:

- type: proxmox
  url: https://proxmox.local
  token: PASTE TOKEN ID # example root@pam!glance
  secret: PASTE SECRET

Go to Datacenter -> Permissions -> Add -> Api Token Permission.