add cluster resource mappings configuration

[WillPower3309]

Options for setting up cluster mappings (particularly PCI) would be really useful to users. This can be done via the API: https://pve.proxmox.com/pve-docs/api-viewer/index.html#/cluster/mapping

Testing would need to be done to ensure that the PUT requests are idempotent, but if so, could be ran on the systemd service startup.

[WillPower3309]

Depending on the maintainer's thoughts, we could also (on service start) remove all mappings and then recreate them based on the option's set value, which would favour the nix setting vs the gui setting

[JulienMalka]

Are you willing to implement this or is this just a feature request?

[WillPower3309]

Are you willing to implement this or is this just a feature request?

I'm willing to implement it, was curious about your thoughts on the mapping removal on start up (making the nix setting the source of truth over the gui one)