Support for disk image as a template source for proxmoxmachine

[3deep5me]

Describe the solution you'd like
I would like to use disk images (qcow/img) instead of a VM-Templates inside the proxmoxmachine/template.

Anything else you would like to add:
With the Import feature of proxmox its possible to download/upload images over the UI/API. VM-Images could be then easier shared. We could then (if we want) build images like VMware does is:
https://github.com/kubernetes-sigs/cluster-api-provider-vsphere

s. https://forum.proxmox.com/threads/api-endpoint-for-disk-import.169019/#post-787225