[PATCH SERIES v4] Add ability to prevent suggesting previously used VM/CT IDs

[Severen Redwood]

Hi everyone,

This is another small update to my previous patch series [1]
adding optional support for preventing PVE from suggesting
previously used VM/CT IDs. Aaron had some small style nits, so
I've addressed those and also added the Reviewed-by and
Tested-by commit trailers he offered.

Note when building this patch series that the pve-cluster
patches must be applied and built first to prevent the build
of pve-manager from failing.

Thanks,
Severen

[1]: https://lore.proxmox.com/pve-devel/mailman.716.1730772112.332.pve-devel@lists.proxmox.com/T/#u