Add more proxmox tags to the vms

[firecyberice]

Describe the solution you'd like
Right now there are two tags present for the vms in proxmox:

• go-proxmox+cloud-init (What is the value / reason of this?)
• ip_net0_<the IP of the vm>

It would be nice to have additional tags / labels like:

• clustername to identify the cluster of that node
• mgmt cluster name or any other reference to the capi cluster that is managing this vm / workload cluster in case there are more management clusters on that proxmox environment.

Optional:
It would be nice to add custom tags as well (at least at some point in the future)

[mcbenjemaa]

go-proxmox+cloud-init is needed to make sure, we unmount the cloudinit iso and destroy it, before deleting the machine.

we can probably remove it: #73

[mcbenjemaa]

The unmount of cloud-init iso is done.